Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of The St. Joe Company (NYSE:JOE) gained as much as 21% on Thursday on an announcement from the Florida real estate development company that it is selling 382,834 of "non-strategic lands" (mainly timberland) in Northwest Florida to an affiliate of the Church of Jesus Christ of Latter-day Saints for $565 million. The company also reported its third-quarter results on Thursday morning

So what: Given that the land in question had a carrying value of $54 million of St. Joe's balance sheet, the company will realize a cool half-billion dollar profit on the sale. Keeping in mind that St. Joe's market capitalization is less than $2 billion, that's what I call unlocking shareholder value!

In commenting on the sale, CEO Park Brady:

This sale of timberland will help the Company concentrate on its core business activity of real estate development in Northwest Florida. The proceeds from the sale will provide the Company with significant liquidity and numerous opportunities to create long-term value for our shareholders.

Now what: St. Joe has long been a controversial stock in the value investing community. Bruce Berkowtiz's Fairholme Capital Management is the largest shareholder, with 27% of the shares outstanding as of June 30, according to data from S&P Capital IQ. Meanwhile, Greenlight Capital's David Einhorn detailed his "short" thesis for the stock at an investment conference in October 2010. While today's announcement is a victory for the longs, including Berkowitz, I wouldn't recommend individual investors invest in St. Joe. It belongs in the the "too-hard pile," to use a phrase coined by another value investor, Warren Buffett.

Fool contributor Alex Dumortier, CFA has no position in any stocks mentioned; you can follow him on Twitter @longrunreturns. The Motley Fool has no position in any of the stocks mentioned, either. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.