Smith & Wesson ( SWHC) was among the biggest small-cap losers in a down session Tuesday, plummeting some 40% on disappointing preliminary results.

The Springfield, Mass., gunmaker cut its year-over-year revenue growth prediction by at least 20 percentage points to between 36% and 40%, meaning total sales of $69 million to $71 million. Analysts polled by Thomson Financial are looking for $82.4 million. Income should range between 5 cents and 7 cents a share, at least a nickel below the mean. Shares were falling $7.92 to $12.17.

Laser-eye surgery outfit LCA-Vision ( LCAV) tumbled 32.7% after predicting that fourth-quarter income will be "significantly below" last year's 27 cents a share, which effectively pushes full-year guidance well below the prior forecast of $1.90 to $2 a share. Cincinnati-based LCA cited an "uncertain business environment."

Third-quarter earnings were in line, but shares traded down $9.19 to $18.92, which helped give a black eye to both the Russell 2000 -- which also tracks Smith & Wesson -- and the S&P SmallCap 600. The sector trackers were off 0.3% and 0.2%, respectively.

Wellman ( WLM) stock booked spectacular losses in heavy trading after the maker of resins and polyester staple fibers said it hired Lazard Freres, "an investment bank with extensive experience in chemical M&A transactions," in order to explore strategic alternatives.

The Fort Mill, S.C., company also reported a third-quarter continuing-operations loss of 81 cents a share against two analysts' estimates for a 64-cent loss, less special items. Shares plunged $1.14, or 63.6%, to 65 cents.

Also foundering in negative territory was Merge Technologies ( MRGE), or Merge Healthcare, which lost 28.1% on word it will restate revenue downward for 2004 through 2006 by a total of some $1 million. Revenue for each of the following quarters will increase by less than $100,000, said the company, through the expiration of the contracts in question.

Shares of the Milwaukee-based company, which develops medical-imaging and information-management software, were trading at $2.46.

Superconductor Technologies ( SCON) ranked among the small-cap winners, however, after inking a deal with China Corporate Credit Assurance to deploy its SuperLink product in 2G and 3G networks in China. Shares of the Santa Barbara, Calif., communication-equipment maker were jumping $1.54, or 13.9%, to $12.64.

And SonicWall ( SNWL), a Californian developer of network-security products, posted non-GAAP third-quarter earnings of $3.9 million, or 6 cents a share -- a penny over per-share estimates. Sales, at $51 million, were a hair under. Shares bounced 16.4% to $10.88.

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