May 01, 2017

MCDONNELL INTERMEDIATE MUNICIPAL BOND FUND

Supplement dated May 22, 2017 to the Prospectus of the McDonnell Intermediate Municipal Bond Fund (the “Fund”), dated May 1, 2017, as may be revised and supplemented from time to time:

Effective May 22, 2017, the Bloomberg Barclays Municipal Bond Index will replace the Bloomberg Barclays 3-15 Year Blend Municipal Bond Index as the Fund’s primary benchmark.

Effective May 22, 2017, the first paragraph within the section “Risk/Return Bar Chart and Table” with respect to the Fund is amended and restated as follows:

The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year and Life-of-Fund periods compare to 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.

Effective May 22, 2017, the “Average Annual Total Returns” table within the section “Risk/Return Bar Chart and Table” with respect to the Fund is amended and restated as follows:

Average Annual Total Returns (for the periods ended December 31, 2016)	Past 1 Year			Life of Fund (12/13/12)
Class Y - Return Before Taxes		-0.55	%		1.48	%
Return After Taxes on Distributions		-0.55	%		1.48	%
Return After Taxes on Distributions and Sale of Fund Shares		0.33	%		1.47	%
Class A - Return Before Taxes		-3.75	%		0.40	%
Class C - Return Before Taxes		-2.42	%		0.45	%
Class T - Return Before Taxes		-3.29	%		0.54	%
Bloomberg Barclays Municipal Bond Index1		0.25	%		2.42	%
Bloomberg Barclays 3-15 Year Blend Municipal Bond Index		-0.05	%		2.14	%

¹ Effective May 22, 2017, the Bloomberg Barclays Municipal Bond Index replaced the Bloomberg Barclays 3-15 Year Blend Municipal Bond Index as the Fund’s primary benchmark because the Fund believes the Bloomberg Barclays Municipal Bond Index, an index which covers the U.S. dollar-denominated long-term tax exempt bond market, is a more appropriate comparison to the Fund’s investment strategies. It is not possible to invest directly in an index.