The most heavily traded stocks were mixed after the closing bell Tuesday, and leading the winners by a wide margin was San Diego-based biotech Cypress Bioscience ( CYPB).

Shares rocketed 87.1% to $15.81 in extremely heavy trading after it and Forest Laboratories ( FRX) announced positive results from a late-phase trial.

The companies said that milnacipran, which is already approved to treat depression, showed statistically significant results in treating fibromyalgia syndrome -- a chronic and painful condition that causes stiffness, severe fatigue and insomnia. Forest shares jumped 8.2% to $56.15.

Aluminum-products makers Alcan ( AL) and Alcoa ( AA) were up more than 2.5% each after Alcan's board unanimously rejected the latter's recent hostile takeout bid, worth roughly $27 billion in cash and stock.

Shanda Interactive Entertainment ( SNDA), a China-based online-games developer, rose 3.4% to $29.60 after earning 36 cents per American depositary share (non-GAAP) in the first quarter. This is 7 cents higher than the average Wall Street estimate, according to Thomson Financial.

Minneapolis medical-equipment maker Medtronic ( MDT) climbed 3.3% to $52.47 after coming in 4 cents above the mean target with non-GAAP earnings of 66 cents a share, or $767 million, in the quarter ended April 27.

Semiconductor maker Advanced Analogic Technologies ( AATI) of Sunnyvale, Calif., was also on the rise after announcing it had "prevailed" in a patent-infringement case brought by Linear Technology ( LLTC). AnalogicTech said all of Linear's claims were found "either non-infringed or invalid" in an "initial determination" by the International Trade Commission. The final determination should issue by Sept. 22. Linear, for its part, traded down 1% to $36.77 in recent extended trading.

Among others on the postclose downswing, Analog Devices ( ADI) fell after predicting fiscal third-quarter income of 37 cents to 41 cents a share (excluding items) on sales ranging between $655 million and $685 million, which leans to the lower end of consensus. The Norwood, Mass., semiconductor company bested targets for the quarter ended May 5, but shares still slid 6% to $38.

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