NEW YORK — Stocks jumped Friday following a better-than-expected rise in profits at Research in Motion Ltd. and on word that Merrill Lynch may have lined up a big cash infusion from a Singapore fund.

The Dow Jones industrial average capped a volatile week with a gain of more than 200 points.

The developments seemed to allay investor fears that economic growth would succumb to tightness in the credit markets. The Federal Reserve also said it would continue with its special biweekly auctions for banks as long as necessary to relieve strains in the short-term debt market.

The Fed said Friday it had auctioned another $20 billion in funds to commercial banks at an interest rate of 4.67 percent. It was the second of four scheduled auctions. The first auction, on Monday, of $20 billion resulted in loans being awarded at an interest rate of 4.65 percent. Two more auctions will occur in early January.