Sallie Mae ( SLM - Get Report) was one of the most actively traded stocks amid a mixed Wednesday late-trading session.

Swirling rumors regarding the instability of the education lender's $25 billion takeout were confirmed when Sallie announced, in a press release shortly before Wednesday's close, that the J.C. Flowers-led investor group doesn't expect to close the deal.

Sallie said it "firmly believes that the buyer group has no contractual basis to repudiate its obligations under the merger agreement and intends to pursue all remedies available to it to the fullest extent permitted by law." After closing lower, shares tripped immediately after the closing bell, but have since more than recovered to add 5.1% to $47.30.

Elsewhere in the green, Bed Bath & Beyond ( BBBY - Get Report) climbed 2.3% after fiscal second-quarter earnings beat Wall Street's estimates. The company reported earnings of $147 million, or 55 cents a share, 3 cents better than the average per-share estimate from Thomson Financial. A year ago, the Union, N.J.-based domestic-products retailer made 51 cents a share.

Bed Bath & Beyond also said it will buy back another $1 billion worth of its shares on completion of its current authorization. Shares were recently up 57 cents to $34.40.

Siga Technologies ( SIGA - Get Report) leapt 12.5% to $4.06, after the New York biotech company said its ST-246 smallpox drug candidate showed "100% protection against death" in preclinical testing on cynomolgus monkeys showing signs of monkeypox infection. The study was conducted at the U.S. Army Medical Institute of Infectious Diseases.

On the other hand, data-storage-technology purveyor Xyratex ( XRTX) pegged fiscal-third-quarter earnings and revenue well below Wall Street estimates. The Britain-based firm expects non-GAAP earnings of between 28 cents and 40 cents a share on a top line of $236 million to $256 million. Analysts are seeking 48 cents a share on $267.1 million in revenue.

Xyratex also edged past second-quarter Street targets, but shares were still sliding $1.06, or 5.6%, to $17.75.

Paychex ( PAYX - Get Report) also slipped on soft guidance, despite beating expectations for fiscal first-quarter earnings. Fiscal 2008 income is now projected to grow just 12% to 14% year-over-year, down at least 4 percentage points from the prior outlook. Corporate investment earnings should get hit particularly hard, with an expected drop of between 35% and 40%, vs. the prior estimate for a gain of 20% to 25%.

The Rochester, N.Y.-based purveyor of payroll-processing services blamed this on stock-repurchasing expenses and a loss of tax benefits related to its investment portfolios, among other things. Shares were off 19 cents to $43.39.