Among the stock activity stories for Monday, Sept. 22, from AP Financial News:

NEW YORK (AP) -- Shares of Ariad Pharmaceuticals Inc. fell Tuesday after the company said it received an unfavorable ruling in a patent dispute against Amgen Inc.

NEW YORK (AP) -- Shares of U.S. Bancorp dove Monday as investors questioned the effectiveness of the government's bailout plan, and an analyst downgraded the shares to "Sell."

NEW YORK (AP) -- Shares of PNC Financial Services Group Inc. dropped Monday amid a sell-off in the financial sector and as an analyst downgraded the stock to "Hold," citing a recent run-up in price.

NEW YORK (AP) -- Astoria Financial Corp. shares slumped Monday after research firm Stifel, Nicolaus downgraded the stock, advising investors to take profits following sharp gains last week.