Summary Prospectus
March 31, 2017, as revised May 1, 2017

Loomis Sayles Dividend Income Fund

Ticker Symbol: Class A (LSCAX), Class C (LSCCX), Class N (LDINX), Class T (LSCTX) and Class Y (LSCYX)

Before you invest, you may want to review the Fund's Prospectus, which contains more information about the Fund and its risks. You can find the Fund's Prospectus and other information about the Fund online at ngam.natixis.com/funddocuments. You can also get this information at no cost by calling 800-225-5478 or by sending an e-mail request to NatixisFunds@ngam.natixis.com. The Fund's Prospectus and Statement of Additional Information, each dated March 31, 2017, as may be revised or supplemented from time to time, are incorporated by reference into this Summary Prospectus.

Investment Goal

The Fund's investment goal is high total return through a combination of current income and capital appreciation.

Fund Fees & Expenses

The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Natixis Fund Complex. More information about these and other discounts is available from your financial professional and in the section "How Sales Charges Are Calculated" on page 41 of the Prospectus, in Appendix A to the Prospectus and on page 101 in the section "Reduced Sales Charges" of the Statement of Additional Information ("SAI").

Shareholder Fees

(fees paid directly from your investment)	Class A		Class C		Class N	Class T		Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	5.75	%	None		None	2.50	%	None
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	None *		1.00	%	None	None		None
Redemption fees	None		None		None	None		None

*A 1.00% contingent deferred sales charge ("CDSC") may apply to certain purchases of Class A shares of $1,000,000 or more that are redeemed within eighteen months of the date of purchase.

Annual Fund Operating Expenses

(expenses that you pay each year as a percentage of the value of your investment)	Class A		Class C		Class N		Class T		Class Y
Management fees	0.60	%	0.60	%	0.60	%	0.60	%	0.60	%
Distribution and/or service (12b-1) fees	0.25	%	1.00	%	0.00	%	0.25	%	0.00	%
Other expenses	0.66	%	0.66	%	0.58	% 1	0.66	% 1	0.66	%
Total annual fund operating expenses	1.51	%	2.26	%	1.18	%	1.51	%	1.26	%
Fee waiver and/or expense reimbursement 2,3	0.41	%	0.41	%	0.38	%	0.41	%	0.41	%
Total annual fund operating expenses after fee waiver and/or expense reimbursement	1.10	%	1.85	%	0.80	%	1.10	%	0.85	%

1Other expenses are estimated for the current fiscal year.

2Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.10%, 1.85%, 0.80%, 1.10% and 0.85% of the Fund's average daily net assets for Class A, C, N, T and Y shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through March 31, 2018 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Fund's Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below the applicable expense limitations for Class A, C, N, T and Y shares. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fee/expense was waived/reimbursed.

3NGAM Advisors, L.P. ("NGAM Advisors") has given a binding contractual undertaking to the Fund to reimburse any and all transfer agency expenses for Class N shares. This undertaking is in effect through March 31, 2018 and may be terminated before then only with the consent of the Fund's Board of Trustees.

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same, except that the example is based on the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement for the first year and on the Total Annual Fund Operating Expenses for the remaining periods. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

1

Fund Summary

If shares are redeemed:	1 year		3 years		5 years		10 years
Class A	$	681	$	987	$	1,315	$	2,240
Class C	$	288	$	667	$	1,173	$	2,563
Class N	$	82	$	337	$	612	$	1,398
Class T	$	359	$	676	$	1,015	$	1,972
Class Y	$	87	$	359	$	652	$	1,486

If shares are not redeemed:	1 year		3 years		5 years		10 years
Class C	$	188	$	667	$	1,173	$	2,563

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During its most recently ended fiscal year, the Fund's portfolio turnover rate was 35% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

Under normal market conditions, the Fund will invest at least 80% of its assets in dividend-paying equity securities. Equity securities purchased by the Fund may include common stocks, preferred stocks, warrants, interests in real estate investment trusts ("REITs") and securities convertible into common or preferred stocks. A significant majority of the equity securities purchased by the Fund will be traded on a U.S. exchange and denominated in U.S. dollars. The Fund's non-U.S. equity investments, which will consist generally of American Depositary Receipts, but may include direct foreign investments as well, will be limited to 20% of the Fund's assets. Although certain equity securities purchased by the Fund may be issued by domestic companies incorporated outside of the United States, the Adviser does not consider these securities to be foreign if they are included in U.S. equity indices published by S&P Global Ratings or Russell Investments. The Fund focuses on stocks of large capitalization companies, but the Fund may invest in companies of any size.

In deciding which securities to buy and sell, the Adviser seeks to identify companies that it believes are, among other things, attractively valued based on the Adviser's estimate of intrinsic value and have a strong track-record and/or potential for high dividend yield. The Adviser generally emphasizes high dividend yielding securities, but also attempts to balance risk and return and assess the future dividend paying ability of the issuers of such securities. The Adviser expects that the Fund's yield, which reflects the level of dividends paid by the Fund, will exceed the yield of the S&P 500^® Index under normal market conditions. The Adviser generally seeks to find value by selecting individual stocks that it believes are attractive, rather than by attempting to achieve investment growth by rotating the Fund's holdings among various sectors of the economy.

The Fund may also purchase and sell (write) options for hedging and investment purposes and invest in securities issued pursuant to Rule 144A under the Securities Act of 1933 ("Rule 144A securities"). Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

Principal Investment Risks

The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund.

Credit/Counterparty Risk: Credit/counterparty risk is the risk that the issuer or guarantor of a fixed-income security, or the counterparty to a derivatives or other transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations. The Fund will be subject to credit risks with respect to the counterparties of its derivative transactions. Many of the protections afforded to participants on organized exchanges, such as the performance guarantee of an exchange clearing house, are not available in connection with over-the-counter ("OTC") derivative transactions, such as OTC options. As a result, in instances when the Fund enters into OTC derivative transactions, the Fund will be subject to the risk that its counterparties will not perform their obligations under the transactions and that the Fund will sustain losses or be unable to realize gains.

Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may be subject to currency risk because it may invest in securities or other instruments denominated in, or that generate income denominated in, foreign currencies.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including options) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund's exposure to securities market values, interest rates or currency exchange rates. It is possible that the Fund's liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks

2

Fund Summary

than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those that would have occurred had derivatives not been used. The Fund's use of derivatives involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than the initial margin required to initiate derivatives positions. There is also the risk that the Fund may be unable to terminate or sell a derivatives position at an advantageous time or price. The Fund's derivative counterparties may experience financial difficulties or otherwise be unwilling or unable to honor their obligations, possibly resulting in losses to the Fund.

Equity Securities Risk: The value of the Fund's investments in equity securities could be subject to unpredictable declines in the value of individual securities and periods of below-average performance in individual securities or in the equity market as a whole. Value stocks can perform differently from the market as a whole and from other types of stocks. Value stocks also present the risk that their lower valuations fairly reflect their business prospects and that investors will not agree that the stocks represent favorable investment opportunities, and they may fall out of favor with investors and underperform growth stocks during any given period. The Fund's focus on dividend-paying equity securities could cause the Fund to underperform the broader equity market if such securities are out of favor and a sharp rise in interest rates or an economic downturn could cause companies to reduce or eliminate their dividends. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer's bonds generally take precedence over the claims of those who own preferred stock or common stock. Rule 144A securities may be less liquid than other equity securities.

Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit/counterparty and information risks. The Fund's investments in foreign securities also are subject to foreign currency fluctuations and other foreign currency-related risks. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity.

Large Investor Risk: Ownership of shares of the Fund may be concentrated in one or a few large investors. Such investors may redeem shares in large quantities or on a frequent basis. Redemptions by a large investor can affect the performance of the Fund, may increase realized capital gains, including short-term capital gains taxable as ordinary income, may accelerate the realization of taxable income to shareholders and may increase transaction costs. These transactions potentially limit the use of any capital loss carryforwards and certain other losses to offset future realized capital gains (if any). Such transactions may also increase the Fund's expenses.

Liquidity Risk: Liquidity risk is the risk that the Fund may be unable to find a buyer for its investments when it seeks to sell them or to receive the price it expects. Decreases in the number of financial institutions willing to make markets in the Fund's investments or in their capacity or willingness to transact may increase the Fund's exposure to this risk. Events that may lead to increased redemptions, such as market disruptions or increases in interest rates, may also negatively impact the liquidity of the Fund's investments when it needs to dispose of them. If the Fund is forced to sell its investments at an unfavorable time and/or under adverse conditions in order to meet redemption requests, such sales could negatively affect the Fund. Securities acquired in a private placement, such as Rule 144A securities, are generally subject to greater liquidity risk because they are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Non-exchange traded derivatives are generally subject to greater liquidity risk as well. Liquidity issues may also make it difficult to value the Fund's investments.

Management Risk: A strategy used by the Fund's portfolio managers may fail to produce the intended result.

Market/Issuer Risk: The market value of the Fund's investments will move up and down, sometimes rapidly and unpredictably, based upon overall market and economic conditions, as well as a number of reasons that directly relate to the issuers of the Fund's investments, such as management performance, financial condition and demand for the issuers' goods and services.

REITs Risk:  Investments in the real estate industry, including REITs, are particularly sensitive to economic downturns and are sensitive to factors such as changes in real estate values, property taxes and tax laws, interest rates, cash flow of underlying real estate assets, occupancy rates, government regulations affecting zoning, land use and rents and the management skill and creditworthiness of the issuer. Companies in the real estate industry also may be subject to liabilities under environmental and hazardous waste laws. In addition, the value of a REIT is affected by changes in the value of the properties owned by the REIT or mortgage loans held by the REIT. REITs are also subject to default and prepayment risk. Many REITs are highly leveraged, increasing their risk. The Fund will indirectly bear its proportionate share of expenses, including management fees, paid by each REIT in which it invests in addition to the expenses of the Fund.

Small- and Mid-Capitalization Companies Risk: Compared to large-capitalization companies, small- and mid-capitalization companies are more likely to have limited product lines, markets or financial resources. Stocks of these companies often trade less frequently and in limited volume and their prices may fluctuate more than stocks of large-capitalization companies. As a result, it may be relatively more difficult for the Fund to buy and sell securities of small- and mid-capitalization companies.

Valuation Risk: This is the risk that the Fund has valued certain securities at a higher price than the price at which they can be sold. This risk may be especially pronounced for investments, such as derivatives, that may be illiquid or may become illiquid.

3

Fund Summary

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by comparing the Fund's one-year and life-of-fund performance with two broad measures of market performance. The Fund's past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund's shares. A sales charge will reduce your return.

Total Returns for Class A Shares

Highest Quarterly Return:
First Quarter 2013,11.13%
Lowest Quarterly Return:
Third Quarter 2015,-7.66%

Average Annual Total Returns
(for the periods ended December 31, 2016)	Past 1 Year		Life of Fund (3/30/12)
Class A - Return Before Taxes	7.67	%	9.96	%
Return After Taxes on Distributions	6.90	%	7.47	%
Return After Taxes on Distributions and Sale of Fund Shares	4.89	%	7.33	%
Class C - Return Before Taxes	12.26	%	10.50	%
Class T - Return Before Taxes	11.38	%	10.74	%
Class Y - Return Before Taxes	14.46	%	11.60	%
S&P 500‌® Index	11.96	%	12.64	%
Russell 1000‌® Value Index	17.34	%	13.10	%

The Fund did not have Class N or Class T shares outstanding during the periods shown above. The returns of Class N and Class T shares would have been substantially similar to the returns of the Fund's other share classes because they would have been invested in the same portfolio of securities and would only differ to the extent the other share classes did not have the same expenses. Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T shares.

The Fund revised its investment strategies on October 15, 2014 and July 18, 2016; performance may have been different had the current investment strategies been in place for all periods shown.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.

Management

Investment Adviser

Loomis, Sayles & Company, L.P. ("Loomis Sayles")

Portfolio Managers

Arthur J. Barry, CFA^®, Vice President of the Adviser, has served as a portfolio manager of the Fund since 2012.

4

Fund Summary

Purchase and Sale of Fund Shares

Class A and C Shares

The following chart shows the investment minimums for various types of accounts:

Type of Account	Minimum Initial Purchase		Minimum Subsequent Purchase
Any account other than those listed below	$	2,500	$	100
For shareholders participating in Natixis Funds' Investment Builder Program	$	1,000	$	50
For Traditional IRA, Roth IRA, Rollover IRA, SEP-IRA and Keogh plans using the Natixis Funds' prototype document (direct accounts, not held through intermediary)	$	1,000	$	100
Coverdell Education Savings Accounts using the Natixis Funds' prototype document (direct accounts, not held through intermediary)	$	500	$	100

Class N Shares

Class N shares of the Fund are subject to a $1,000,000 initial investment minimum. There is no initial investment minimum for certain retirement plans and funds of funds that are distributed by NGAM Distribution, L.P. There is no subsequent investment minimum for these shares. In its sole discretion, NGAM Distribution, L.P. may waive the investment minimum requirement for accounts as to which the relevant financial intermediary has provided assurances, in writing, that the accounts will be held in omnibus fashion beginning no more than two years following the establishment date of such accounts in Class N.

Class T Shares

Class T shares of the Fund may only be purchased by investors who are investing through an authorized third party, such as a broker-dealer or other financial intermediary, that has entered into a selling agreement with NGAM Distribution, L.P. Investors may not hold Class T shares directly with the Fund. Class T shares are subject to a minimum initial investment of $2,500 and a minimum subsequent investment of $100.  Not all financial intermediaries make Class T shares available to their clients.

Class Y Shares

Class Y shares of the Fund may be purchased by the following entities at the following investment minimums.

A minimum initial investment of $100,000 and the minimum subsequent investment of $100 for:

■

Other mutual funds, endowments, foundations, bank trust departments or trust companies.

There is no initial or subsequent investment minimum for:

■

Wrap Fee Programs of certain broker-dealers, the advisers or NGAM Distribution, L.P. Please consult your financial representative to determine if your wrap fee program is subject to additional or different conditions or fees.

■

Certain Retirement Plans. Please consult your retirement plan administrator to determine if your retirement plan is subject to additional or different conditions or fees.

■

Certain Individual Retirement Accounts if the amounts invested represent rollover distributions from investments by any of the retirement plans invested in the Fund.

■

Clients of a Registered Investment Adviser where the Registered Investment Adviser receives an advisory, management, or consulting fee.

■

Fund Trustees, former Fund trustees, employees of affiliates of the Natixis Funds and other individuals who are affiliated with any Natixis Fund (this also applies to any spouse, parents, children, siblings, grandparents, grandchildren and in-laws of those mentioned) and Natixis affiliate employee benefit plans.

Due to operational limitations at your financial intermediary, certain wrap fee programs, retirement plans, individual retirement accounts and accounts of registered investment advisers may be subject to the investment minimums described above.

The Fund's shares are available for purchase and are redeemable on any business day through your investment dealer, directly from the Fund by writing to the Fund at Natixis Funds, P.O. Box 219579, Kansas City, MO 64121-9579, by exchange, by wire, by internet at ngam.natixis.com (certain restrictions may apply), through the Automated Clearing House system, or, in the case of redemptions, by telephone at 800-225-5478 or by the Systematic Withdrawal Plan. See section "How Fund Shares are Priced" for details.

Tax Information

Fund distributions are generally taxable to you as ordinary income or capital gains, except for distributions to retirement plans and other investors that qualify for tax-advantaged treatment under U.S. federal income tax law generally. Investments in such tax-advantaged plans will generally be taxed only upon withdrawal of monies from the tax-advantaged arrangement.

5

Fund Summary

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase shares of the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies may pay the intermediary for the sale of the Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary's website for more information.

UCI77-0517

6