497

Prospectus Supplement	May 18, 2018
Putnam Convertible Securities Fund
Prospectus dated February 28, 2018

Beginning on May 21, 2018, the fund will offer class R6 shares to:

• employer-sponsored retirement plans that are clients of third-party administrators (including affiliates of Putnam) that have entered into agreements with Putnam;

• investors purchasing shares through an asset-based fee program that is sponsored by a registered broker-dealer or other financial institution;

• investors purchasing shares through a commission-based platform of a registered broker-dealer or other financial institution that charges the shareholder additional fees or commissions, other than those described in the prospectus and statement of additional information, and that has entered into an agreement with Putnam Retail Management to offer class R6 shares through such a program;

• corporations, endowments, foundations and other institutional investors that have been approved by Putnam; and

• unaffiliated investment companies (whether registered or private) that have been approved by Putnam.

The prospectus is supplemented as follows to add information about class R6 shares.

The front cover page is supplemented to add class R6 shares to the list of shares to which the prospectus relates, and to indicate that the fund’s symbol for class R6 shares is PCNTX.

The following information is added to similar disclosure for the fund under Fund summary — Fees and expenses:

Shareholder fees (fees paid directly from your investment)

Share class	Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, whichever is lower)
Class R6	NONE	NONE

Annual fund operating expenses
(expenses you pay each year as a percentage of the value of your investment)

Share class	Management fees	Distribution and service (12b-1) fees	Other expenses	Total annual fund operating expenses
Class R6	0.63%	N/A	0.10%=	0.73%

= Other expenses are based on expenses of class A shares for the fund’s last fiscal year, restated to reflect the lower investor servicing fees applicable to class R6 shares.

Example

The following hypothetical example is intended to help you compare the cost of investing in the fund with the cost of investing in other funds. It assumes that you invest $10,000 in the fund for the time periods indicated and then, except as indicated, redeem all your

shares at the end of those periods. It assumes a 5% return on your investment each year and that the fund’s operating expenses remain the same. Your actual costs may be higher or lower.

Share class	1 year	3 years	5 years	10 years
Class R6	$75	$233	$406	$906

XML

Putnam Convertible Securities Fund

Prospectus Supplement	May 18, 2018
Putnam Convertible Securities Fund
Prospectus dated February 28, 2018

Beginning on May 21, 2018, the fund will offer class R6 shares to:

• employer-sponsored retirement plans that are clients of third-party administrators (including affiliates of Putnam) that have entered into agreements with Putnam;

• investors purchasing shares through an asset-based fee program that is sponsored by a registered broker-dealer or other financial institution;

• investors purchasing shares through a commission-based platform of a registered broker-dealer or other financial institution that charges the shareholder additional fees or commissions, other than those described in the prospectus and statement of additional information, and that has entered into an agreement with Putnam Retail Management to offer class R6 shares through such a program;

• corporations, endowments, foundations and other institutional investors that have been approved by Putnam; and

• unaffiliated investment companies (whether registered or private) that have been approved by Putnam.

The prospectus is supplemented as follows to add information about class R6 shares.

The front cover page is supplemented to add class R6 shares to the list of shares to which the prospectus relates, and to indicate that the fund’s symbol for class R6 shares is PCNTX.

The following information is added to similar disclosure for the fund under Fund summary — Fees and expenses:

Shareholder fees (fees paid directly from your investment)

Share class	Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, whichever is lower)
Class R6	NONE	NONE

Annual fund operating expenses
(expenses you pay each year as a percentage of the value of your investment)

Share class	Management fees	Distribution and service (12b-1) fees	Other expenses	Total annual fund operating expenses
Class R6	0.63%	N/A	0.10%=	0.73%

= Other expenses are based on expenses of class A shares for the fund’s last fiscal year, restated to reflect the lower investor servicing fees applicable to class R6 shares.

Example

The following hypothetical example is intended to help you compare the cost of investing in the fund with the cost of investing in other funds. It assumes that you invest $10,000 in the fund for the time periods indicated and then, except as indicated, redeem all your

shares at the end of those periods. It assumes a 5% return on your investment each year and that the fund’s operating expenses remain the same. Your actual costs may be higher or lower.

Share class	1 year	3 years	5 years	10 years
Class R6	$75	$233	$406	$906

Shareholder fees (fees paid directly from your investment)

Shareholder Fees	Putnam Convertible Securities Fund Class R6
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, whichever is lower)	none

Annual fund operating expenses
(expenses you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Putnam Convertible Securities Fund Class R6
Management fees	0.63%
Distribution and service (12b-1) fees
Other expenses	0.10%	[1]
Total annual fund operating expenses	0.73%

Example

The following hypothetical example is intended to help you compare the cost of investing in the fund with the cost of investing in other funds. It assumes that you invest $10,000 in the fund for the time periods indicated and then, except as indicated, redeem all your shares at the end of those periods. It assumes a 5% return on your investment each year and that the fund’s operating expenses remain the same. Your actual costs may be higher or lower.

Expense Example	Expense Example, with Redemption, 1 Year	Expense Example, with Redemption, 3 Years	Expense Example, with Redemption, 5 Years	Expense Example, with Redemption, 10 Years
Putnam Convertible Securities Fund | Class R6 | USD ($)	75	233	406	906

[1] Other expenses are based on expenses of class A shares for the fund's last fiscal year, restated to reflect the lower investor servicing fees applicable to class R6 shares.

XML

Label

Element

Value

Risk Return Abstract

rr_RiskReturnAbstract

Document Type

dei_DocumentType

497

Document Period End Date

dei_DocumentPeriodEndDate

May 18, 2018

Registrant Name

dei_EntityRegistrantName

PUTNAM CONVERTIBLE SECURITIES FUND

Central Index Key

dei_EntityCentralIndexKey

0000081247

Amendment Flag

dei_AmendmentFlag

false

Trading Symbol

dei_TradingSymbol

PCONX

Document Creation Date

dei_DocumentCreationDate

May 14, 2018

Document Effective Date

dei_DocumentEffectiveDate

May 18, 2018

Prospectus Date

rr_ProspectusDate

Feb. 18, 2018

Putnam Convertible Securities Fund

Risk Return Abstract

rr_RiskReturnAbstract

Supplement Text

PCONX_SupplementText

Prospectus Supplement	May 18, 2018
Putnam Convertible Securities Fund
Prospectus dated February 28, 2018

Beginning on May 21, 2018, the fund will offer class R6 shares to:

• employer-sponsored retirement plans that are clients of third-party administrators (including affiliates of Putnam) that have entered into agreements with Putnam;

• investors purchasing shares through an asset-based fee program that is sponsored by a registered broker-dealer or other financial institution;

• investors purchasing shares through a commission-based platform of a registered broker-dealer or other financial institution that charges the shareholder additional fees or commissions, other than those described in the prospectus and statement of additional information, and that has entered into an agreement with Putnam Retail Management to offer class R6 shares through such a program;

• corporations, endowments, foundations and other institutional investors that have been approved by Putnam; and

• unaffiliated investment companies (whether registered or private) that have been approved by Putnam.

The prospectus is supplemented as follows to add information about class R6 shares.

The front cover page is supplemented to add class R6 shares to the list of shares to which the prospectus relates, and to indicate that the fund’s symbol for class R6 shares is PCNTX.

The following information is added to similar disclosure for the fund under Fund summary — Fees and expenses:

Shareholder fees (fees paid directly from your investment)

Share class	Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, whichever is lower)
Class R6	NONE	NONE

Annual fund operating expenses
(expenses you pay each year as a percentage of the value of your investment)

Share class	Management fees	Distribution and service (12b-1) fees	Other expenses	Total annual fund operating expenses
Class R6	0.63%	N/A	0.10%=	0.73%

= Other expenses are based on expenses of class A shares for the fund’s last fiscal year, restated to reflect the lower investor servicing fees applicable to class R6 shares.

Example

The following hypothetical example is intended to help you compare the cost of investing in the fund with the cost of investing in other funds. It assumes that you invest $10,000 in the fund for the time periods indicated and then, except as indicated, redeem all your

shares at the end of those periods. It assumes a 5% return on your investment each year and that the fund’s operating expenses remain the same. Your actual costs may be higher or lower.

Share class	1 year	3 years	5 years	10 years
Class R6	$75	$233	$406	$906

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual fund operating expenses
(expenses you pay each year as a percentage of the value of your investment)

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Other expenses are based on expenses of class A shares for the fund’s last fiscal year, restated to reflect the lower investor servicing fees applicable to class R6 shares.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The following hypothetical example is intended to help you compare the cost of investing in the fund with the cost of investing in other funds. It assumes that you invest $10,000 in the fund for the time periods indicated and then, except as indicated, redeem all your shares at the end of those periods. It assumes a 5% return on your investment each year and that the fund’s operating expenses remain the same. Your actual costs may be higher or lower.

Putnam Convertible Securities Fund | Class R6

Risk Return Abstract

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, whichever is lower)

rr_MaximumDeferredSalesChargeOverOther

none

Management fees

rr_ManagementFeesOverAssets

0.63%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

Other expenses

rr_OtherExpensesOverAssets

0.10%

^[1]

Total annual fund operating expenses

rr_ExpensesOverAssets

0.73%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 75

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

233

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

406

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 906

[1] Other expenses are based on expenses of class A shares for the fund's last fiscal year, restated to reflect the lower investor servicing fees applicable to class R6 shares.