UPDATE 1-St. Joe stock hits 52-wk low on Einhorn's comments

* Hedge fund manager David Einhorn sent shares tumbling

* Options market active on Einhorn's comments

* Shares down 11 pct (Adds details on options, strategist's comment, byline, updates share price)

By Alina Selyukh

NEW YORK, Oct 14 (Reuters) - St Joe Co (JOE.N) shares fell for a second consecutive day on Thursday, a day after hedge fund manager David Einhorn raised concerns the company was overvaluing Florida real estate holdings on its books.

The stock closed down 11 percent at $19.72 on the New York Stock Exchange, hitting its lowest level since April 2009.

Einhorn, who in early 2008 made a prescient call on Lehman Brothers' accounting troubles before the company collapsed that fall, holds a short position on the company's shares and is betting that their value will fall.

On Wednesday, Einhorn made a presentation on St. Joe at the annual Value Investing Congress in New York, sending the shares tumbling nearly 10 percent. [ID:nN13258241]

"Obviously Einhorn's word has an incredible amount of credibility and influence," said Joe Kinahan, chief derivatives strategist at TD Ameritrade. "When he talks as poorly about a stock as he did about St Joe's yesterday, it causes investors to look at the stock with a sense of doubt."

St. Joe shares underperformed the relatively flat real estate sector index .DJUSRE, and the company was the fourth biggest loser on the New York Stock Exchange (PL.N).

A spokesman for St. Joe said the company had no comment on the stock price decline.

The options market also responded to Einhorn's comments, with about 16,000 puts and 12,000 calls traded in St Joe, or 8.9 times the typical levels by 3:06 p.m. EDT, according to options analytics firm Trade Alert.

Similar to Wednesday, traders favored the November and January put options, giving them the right to sell the stock at $20 per share, said Frederic Ruffy, options strategist at Web information site WhatsTrading.com in New York.

Investors often turn to equity put options, which grant them the right to sell shares at a fixed price any time until expiration, to speculate on potential share price weakness.

"It is likely that some option investors are liquidating positions, but others are opening new bearish trades in anticipation of additional short-term weakness," Ruffy said.

Einhorn's presentation on the Florida developer included photos and video of St. Joe's beachfront properties that he said had undersold.

He said St. Joe, Florida's largest landowner with 577,000 acres, was marking much of its land as "pre-development" or "in development" when no construction appeared to take place at all.

"Joe needs to take additional impairments," he told investors at the conference.

St. Joe in a statement on Wednesday touted northwest Florida's "miles of sugar-white sand beaches" and said its balance sheet was "virtually debt-free."

Einhorn said the company should sell itself, but that the prospect was unlikely at the stock's current valuation. (Reporting by Alina Selyukh and Jennifer Ablan. Additional reporting by Doris Frankel in Chicago. Editing by Robert MacMillan)