A number of stocks were pulled down by poor financials and guidance after the closing bell Wednesday, including a tumbling NutriSystem ( NTRI).

Shares lost 22.5% after the Horsham, Pa.-based provider of weight-management products projected third-quarter earnings of between 62 cents and 66 cents a share. The company sees revenue of some $188 million. The results include about $600,000 in costs related to a defunct proposed buyout. Analysts polled by Thomson Financial are looking for 82 cents a share, excluding extraordinary items, on revenue of $206.7 million.

The company also added $100 million to its existing share-buyback program, but shares still surrendered $10.72 to $36.85.

Wireless Ronin Technologies ( RNIN), a maker of digital-signage products, plummeted 20.9% to $4.70, after ratcheting down its 2007 sales guidance by at least $10 million. The company now sees revenue of between $6 million and $8 million, vs. Wall Street's expectation of $18 million. The Minnetonka, Minn., company believes that a "significant portion" of the previously expected revenue will be realized in 2008.

Also slipping on a lower outlook was Wet Seal ( WTSLA), a teenage girls' apparel retailer. Shares slid 15% after the Foothill Ranch, Calif., company said that a same-store sales drop of 7.5% to 8.5% will weigh down income to between break-even and 2 cents a share, vs. the prior forecast for 7 cents to 10 cents a share.

The retailer previously forecast same-store sales to rise 1% to 3% from last year. Shares were losing 60 cents to $3.39.

Elsewhere, Smart Modular Technologies ( SMOD) posted non-GAAP income of $10.8 million, or 17 cents a share, in the quarter ended Aug. 31. The results represented a 10.5% per-share fall from last year that comes in 3 cents below Street estimates. Shares of the Fremont, Calif., chipmaker gave up 43 cents, or 5.3%, to $7.54.

Isilon Systems ( ISLN), another tech stock, plunged 16.4% after estimating a third-quarter non-GAAP loss of 8 cents to 10 cents a share against analysts' call for a 3-cent loss. Revenue should also miss the mean target. The Seattle-based company, which makes clustered storage systems for digital content, was off $1.15 to $5.85.

But Immucor ( BLUD), a maker of reagents and automated systems for the blood-transfusion industry, climbed 2.7% on better-than-expected fiscal first-quarter results. The Norcross, Ga., company saw its profit vault 38.9% year-over-year to 25 cents a share, or $17.8 million, on sharply higher revenue of $63.6 million. Analysts were seeking income of 22 cents a share on sales of $59.8 million.

Shares traded up 94 cents to $36.20.