Steve DeLaney of JMP Securities says REITs can borrow against 95% to 97% of a government-backed mortgage security's value in the repo market.

WSJ: HEARD ON THE STREET: Debt Ceiling's Overlooked Flash Crash

As a group, the pure-play investment banks have relied heavily on short-term funding, particularly repo transactions in which counterparties take collateral as security against the cash they lend.

ECONOMIST: Investment banking: Is there a future? | The