Updated from 11:40 a.m. EST

Shares of Cablevision ( CVC) got cheaper Friday after a last-ditch $8.9 billion buyout offer from the cable operator's controlling family disappointed investors.

The stock was recently down 81 cents, or 2.7%, to $28.79 after the Dolan family upped its bid for the cable operator to $30 a share, an increase of 11% over their October offer of $27 a share. The latest bid narrowly topped Thursday's closing price of $29.60.

Cablevision said midday Friday that it a special board committee plans to review the new proposal. It won't comment further on the offer.

The Dolan group -- led by led by Cablevision chairman and founder Charles Dolan and CEO James Dolan -- already owns 20% of the company, which owns New York's Madison Square Garden and three cable networks, among other properties. Investors had widely anticipated a higher bid, and now at least one analyst who expects the company to stay public smells a buying opportunity.

Richard Greenfield, an analyst with Pali Research, said in a research note Friday that he expects the special committee of the Cablevision board reviewing the offer to reject the bid. If Cablevision remains public, it could become a takeover target for competitors such as Time Warner's ( TWX) cable division, Greenfield believes.

"We continue to believe that Cablevision deserves a valuation premium to its industry peers based on its stronger earnings growth, more valuable underlying systems, and a strong likelihood of a Time Warner Cable takeover attempt over the next 12 to 18 months," wrote Greenfield.

He holds a price target on the stock of $33.50, and he said it is "virtually impossible" for the special committee to approve the Dolans' offer unless the acquisition price was increased to at least $31 to $32 a share.

In a release, the Dolan family said $30 a share was its "best and final" offer, and it's only available until next Wednesday. The family also said it would not sell the company, a pledge that Greenfield said displays bad corporate governance.

Greenfield said "multiple bidders (particularly Time Warner Cable) would pay (today) in excess of 33% more than the Dolan's revised $30 offer to take Cablevision private."

The Dolan family justified its offer by pointing to the stock price prior to its initial offer back in October, when the shares were trading below $24. Greenfield said that what actually matters is how cable stocks have traded since then.

"Utilizing our desired time period of relative performance, Cablevision's stock price has underperformed its cable peers, despite superior operating performance and the industry's most valuable assets," Greenfield wrote.