Biogen

(BIIB) - Get Report

was one of the most densely traded losers in after-hours trading Wednesday.

Shares plummeted some 27% after the Cambridge, Mass.-based biotech company said that it

hasn't gotten any definitive buyout offers since putting itself up for sale two months ago. As a result, it has decided to remain an independent company. Shares dove $20.58 to $55.30, far below Biogen's closing price before it put itself on the block.

Select Comfort

(SCSS)

CFO Jim Raabe, meanwhile, said in a postbell conference call that the company's top and bottom lines will come in below its prior deflated guidance, implying it will miss Wall Street's expectations. In October, the bedmaker predicted full-year earnings of 75 cents to 81 cents a share on revenue of between $820 million and $830 million. Analysts are looking for 76 cents a share on $820.6 million in revenue, per Thomson Financial.

Partly due to a "volatile consumer environment," Raabe declined to provide fourth-quarter guidance. He also forecasts "difficult sales trends" into next year, but emphasized that the company remains "confident" in its ability to recover. Shares were falling 14% to $8.67 in light extended trading, following some choppy action.

Bond insurer

Security Capital Assurance

(SCA) - Get Report

, which plunged late in the regular session after Fitch Ratings said it may have a shortfall of

as much as a $2 billion, extended those losses after the closing bell rang. Shares were off another 6.2% to $5.11 in recent after-hours trading.

On the other hand,

ADC Telecommunications

( ADCT) leapt 9.1% after posting

better-than-expected sales of $329.6 million in the fiscal fourth quarter, even though investments in "auction-rate securities" helped pressure it into a GAAP-based loss of 6 cents a share. The Eden Prairie, Minn., communications-equipment also predicted a roughly in-line sequential sales decline of between 3% and 7% in the first quarter. Shares were up $1.53 to $18.27.

Also riding high was

Martek Biosciences

( MATK), which makes nutritional supplements, among other things. The Maryland company said its fiscal fourth-quarter non-GAAP profit more than doubled from last year to $7.5 million, or 23 cents a share. That's 3 cents ahead of Street projections. Sales jumped 22.1% year over year to $82 million, which beats by around $3.6 million. Martek shares were up $3.40, or 14%, to $27.69 in extended trading.