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 SandRidge Energy (NYSE: SD) jumped 11% in early trading after an activist investor proposed an overhaul of the company.

So what: TPG-Axon, a hedge fund that owns 4.5% of the company, sent a letter to the company on Thursday calling for it to fire its CEO, shake up the board, and consider putting the company up for sale.  

Now what: The complaints from the fund had a lot to do with the stock price performance and confidence in the board and CEO. The exuberance of the letter lost its steam quickly and near the end of trading shares are only up 3%. This may lead to some changes at SandRidge but buying today would be purely speculative so you shouldn't change your investment thesis because of today's news.