Lehman Brothers will sell Archstone, a big apartment operator, for $6.5 billion. Buyers Equity Residential and AvalonBay Communities, Archstone’s biggest rivals, will split the assets 60-40 and take on Archstone’s debt, for a total deal value of $16 billion. Lehman collapsed in the financial crisis in 2008, in part because of bad real estate bets, including the $23.7 billion buyout of Archstone. Equity gets 78 properties with 23,110 units; AvalonBay, 66 properties with 22,222 units. Equity’s stock rose 1.5 percent.