The U.S. Federal Reserve (Fed) said it would auction $75 billion under a program announced last week to deliver more liquidity to strained banks and financial companies. In a modification to last week's announcement, the central bank said it would ease the collateral requirements for companies seeking credits under the new plan. The Fed said March 11 it was injecting a total $200 billion to help unfreeze the credit markets. The change announced Thursday would make borrowing from the central bank easier for companies holding some mortgage-backed securities that cannot be easily traded.