Lehman Brothers Holdings Inc. has exercised its right of first offer to acquire 50 percent of the interests in apartment owner Archstone held by Barclays Bank PLC and Bank of America for $1.325 billion.

Prior to the deal, Barclays and Bank of America owned 53 percent of Archstone, with Lehman controlled the other 47 percent. Now the balance shifts to Lehman holding 73.5 percent while Barclays and Bank of America, at least temporarily, retain a 26.5 percent stake.

As a result, Equity Residential, which had entered in a contract to buy the same stake in early December, terminated its purchase agreement with the banks. However, Equity now has until February 19 to act on a separate agreement with the banks and exercise its right to acquire the remaining 26.5 percent stake held by Barclays and Bank of America for $1.325 billion. Lehman retains a right of first offer to match that bid, should Equity decide to exercise its option.

Equity revealed the latest development this morning in an SEC filing.

According to the filing: “If exercised, the acquisition by ERP of the Other Interests will be on substantially the same terms and conditions as set forth in the Purchase Agreement, including being subject to Lehman’s ROFO Right with respect to the Other Interests, except that in the event that ERP offers in excess of $1,325,000,000 and Lehman exercises its ROFO Right with respect to the Other Interests, then certain breakup fee amounts must be paid by the Sellers to ERP as previously disclosed.”

Lehman sought approval from a bankruptcy judge to move forward with the bid and has been steadfast in its attempt to retain control over Archstone since Equity originally announced its deal with Barclays and Bank of America.