A court-appointed examiner said demands from JPMorgan Chase (NYSE:JPM) and Citigroup (NYSE:C) for collateral helped to drive Lehman Brothers into bankruptcy. In other news, Potash Corp. of Saskatchewan (NYSE:POT) sharply raised its first-quarter forecast on Thursday, citing a sharp rebound in demand for potash — a key crop nutrient. Shares jumped over 7% before the bell. Also, Ann Taylor (NYSE:ANN) on Friday swung to a fourth-quarter profit even as sales fell 3% after it controlled inventory and revamped merchandise to help sell more products at full price.