Nymex

( NMX) plunged 3.6% after an analyst at Prudential Equity Group initiated coverage on the exchange with an underweight rating. He said that Nymex faces above-average competition from other exchanges and in the near term it is an unlikely takeout candidate. Shares were trading down $4.71 to $127.50.

Scottish Re

(SCT)

plummeted on news that MassMutual Capital Partners and Cerberus will collectively take a majority stake in the struggling insurer. The two companies will sink $300 million apiece into Scottish Re in exchange for preferred stock that can be converted into ordinary shares. Investors had been hoping for an outright buyout and are worried about the future dilution to the company's stock. Shares were down 79 cents, or 11.9%, to $5.84.

Cohen & Steers

(CNS) - Get Report

tumbled on news that the asset manager will sell 3.5 million of its shares -- 1.5 million of them by Co-Chief Executives Martin Cohen and Robert Steers. Shares were trading down $1.89, or 5%, to $35.96.

Advanta

( ADVNB) jumped after the credit card company raised its full-year 2007 earnings guidance. The Pennsylvania-based company now projects earnings will range between $3.15 and $3.25 a share. The Thomson Financial consensus forecast had the company earning $3.06 a shares. The stock rose $4.26, or 10%, to $46.15.

Ventas

(VTR) - Get Report

fell after the Kentucky real estate investment trust announced it would sell about $200 million of convertible senior notes in a private placement. Shares were down 95 cents, or 2.4%, to $38.55.