LEGG MASON PARTNERS EQUITY TRUST

LEGG MASON BATTERYMARCH S&P 500 INDEX FUND

SUPPLEMENT DATED MARCH 19, 2010

TO THE PROSPECTUS

DATED JANUARY 28, 2010

The following information supplements and to the extent inconsistent therewith, supersedes the information contained in the section of the fund’s Prospectus titled Dividends, distributions and taxes:

Dividends and distributions

The fund generally pays dividends and makes capital gain distributions, if any, typically once or twice a year. The fund may pay additional distributions and dividends at other times if necessary for the fund to avoid a federal tax. The fund expects distributions to be primarily from capital gains. Unless otherwise directed, capital gain distributions and dividends are reinvested in additional fund shares of the same class you hold. You do not pay a sales charge on reinvested distributions or dividends. Alternatively, you can instruct your Service Agent, Funds Investor Services or Institutional Shareholder Services to have your distributions and/or dividends paid in cash. You can change your choice at any time to be effective as of the next distribution or dividend.

If you own Class A shares and hold your shares directly with the fund, you may instruct Funds Investor Services to have your distributions and/or dividends invested in Class A shares of another fund sold by the distributor, subject to the following conditions:

• You have a minimum account balance of $10,000

• The fund is available for sale in your state

To change your election to reinvest your dividends and distributions in shares of another fund, you must notify Funds Investor Services or Institutional Shareholder Services at least three days before the next distribution is to be paid.

Please contact your Service Agent, Funds Investor Services or Institutional Shareholder Services to discuss what options are available to you for receiving your dividends and distributions.

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