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 Knight Capital Group (NYSE: KCG), a financial services and order routing company whose software glitch cost it $461.1 million in just 45 minutes, jumped as much as 21% after receiving an analyst upgrade amid speculation of a takeover.

So what: Analyst Niamh Alexander of research firm Keefe, Bruyette & Woods, upgraded Knight to "market perform" from "underperform" today, and boosted his firm's price target on the company to $2.60 from $2.25. Specifically, Alexander noted as the impetus for the upgrade a story in The Wall Street Journal over the weekend that cites two parties, Getco and Virtu Financial, that could be interested in purchasing Knight's recently maligned market-making division.

Now what: Now you calm down, because analyst upgrades and downgrades, as well as speculation, are rarely ever a good reason to chase a stock higher or lower. We know that Knight's dilutive cash raising plans were going to weigh down the stock for some time, and it's likely to be a few more quarters before we see Knight's business return to normal. I feel the company could be a very long-term turnaround candidate, but I wouldn't allow today's euphoria to take investors for a loop.

Craving more input? Start by adding Knight Capital Group to your free and personalized watchlist so you can keep up on the latest news with the company.