Small-cap stocks hovered above the broader market Wednesday for most of the day as upbeat news surfaced from a variety of sectors.

Cypress Bioscience ( CYPB) was still riding high after surging late Tuesday on positive preliminary results from a late-stage trial of milnacipran for treatment of fibromyalgia syndrome. Shares nearly doubled at $16.37 after a CIBC World Markets analyst upped the stock to outperform. Forest Laboratories ( FRX), which jointly announced these results with Cypress, lately added 2.2% to $53.

Semiconductor Advanced Analogic Technologies ( AATI) also garnered an upgrade -- to buy from hold, at Needham & Co. -- after Tuesday's after-hours announcement of a favorable "initial determination" ruling from a patent-infringement case brought by Linear Technology ( LLTC). After an extended-trading leap, AnalogicTech shares still climbed 16.5% higher to $9.33. Linear slid 3.6% to $35.79.

Cypress and Analogic both supported the Russell 2000, which enjoyed a few hours on the upswing before careening down to flat-line along with the rest of the market. The index was off 0.4% at 836.54.

Also among small-cap gainers today was Mesa Laboratories ( MLAB). Shares vaulted 22.6% to $22.68 after the Colorado-based medical-equipment maker reported fiscal fourth-quarter earnings of $1.4 million, or 44 cents a share, compared with 27 cents a share a year ago. Sales soared 53.6% to $5.3 million.

SenoRx ( SENO), based in California, said the Food and Drug Administration cleared for commercialization its Multi-Lumen Radiation Balloon Applicator for brachytherapy in breast cancer patients. (Brachytherapy involves implanting small radioactive "seeds" that kill cancer cells.) Shares jumped 13.5%, or $1.08, to $9.08.

American Technology ( ATCO), meanwhile, traded some 23% higher to $3.98 after saying the U.S. Navy and Army chose the San Diego-based company's LRAD 500 acoustic hailing and warning device for small vessels and vehicles.

Children's footwear maker Stride Rite ( SRR), which agreed to an $800 million takeout by Payless ShoeSource ( PSS), surged 30.9% to $20.21 and provided strong support to the S&P SmallCap 600, but the index still weighed under the broader market's afternoon slide. The index slipped 2.09 points to 434.22.

Among those pulling down the tracker was Minneapolis medical-device maker Possis Medical ( POSS), which plunged 9.8% to $12.09 after breaking even for the quarter ended April 30 to fall a nickel short of Thomson Financial's per-share earnings consensus for the quarter ended April 30.

Likewise for fellow components Pep Boys ( PBY), an auto-parts retailer, and Maximus ( MMS), a business-services firm. Pep Boys slid 5.6% to $18.82 after coming in below sales estimates for the quarter ended May 5, and Maximus was cut to hold from buy at Stifel Nicolaus, pressuring shares down 4.2% to $41.65.

Elsewhere in negative territory, Vion Pharmaceuticals ( VION) took a 57.4% nosedive to 86 cents after the New Haven, Conn., biotech halted a late-phase study of leukemia drug Cloretazine "pending a detailed review of all of the data from the trial."

TRM ( TRMM), an Oregon-based purveyor of ATM and photocopy services, tumbled 25.5% to $1.81 after announcing dwindling fourth-quarter revenue and a widening loss vs. last year, as well as the resignation of Chief Executive Jeffrey Brotman, who will stay on as a non-executive chairman. His CEO role will be assumed by the current chief operating officer, Richard Stern, as of June 15.