Stocks trended downward after the bell Tuesday, and Chevron ( CVX) was among the decliners. The oil and gas company lost ground after predicting that its third-quarter bottom line will come in "significantly below" the $5.4 billion profit it recorded in the second quarter. The San Ramon, Calif., company blames some of this on one-time items, as well as a "sharp decline in refined-product margins for the downstream business." Shares were down $1.85, or 2%, to $90.95. Also slipping on soft guidance was International Paper ( IP), which said its third-quarter income won't meet the 63-cent per-share analyst consensus, according to Thomson Financial. The Memphis, Tenn.-based paper and packaging company did reaffirm, however, that it expects earnings per share to rise sequentially from last quarter's 52 cents. Shares were off 2.7% to $36.06. Sallie Mae ( SLM) retreated as well, on word the J.C. Flowers-led group's revised takeout bid for the student lender had expired. In announcing this, the buyer group called Sallie's just-announced retaliatory lawsuit regarding the amended offer "meritless." The group, which also includes Bank of America ( BAC) and JPMorgan Chase ( JPM), argued that the College Cost Reduction and Access Act, which will cut education-lending subsidies and was signed into law last month, is a "material adverse effect" as defined under the merger agreement. The group said that Sallie's claim to the contrary is a "misreading of the contract." Sallie shares were flat at $48.50 in recent extended trading. BofA added a penny to $52.58, and JPMorgan was flat at $47.57. Aluminum maker Alcoa ( AA), meanwhile, reported a 3.2% rise in third-quarter continuing-operations income to 64 cents a share, or $558 million. Analysts were looking for 65 cents a share, excluding special items. In addition, the Pittsburgh-based company said it will now buy back as much as 25% of its outstanding shares, up from the prior 10% authorization. Shares were recently up 8 cents to $39.80. Elsewhere, Canada-based Angiotech Pharmaceuticals ( ANPI) jumped 9.5% on positive results from a pivotal trial on its anti-infective 5-Fluorouacil-coated Central Venous Catheter. The study achieved the primary efficacy endpoint and demonstrated an "excellent safety profile," the company said. Shares gained 63 cents to $7.30 in light trading.