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: Biotechnology company Pharmacyclics (Nasdaq: PCYC) soared for a second day in a row -- this time by as much as 12% earlier in the trading session -- following an upgrade from TheStreet Ratings.

So what: I usually leave the right to poke fun at analyst upgrades and downgrades to Foolish colleague Rich Smith -- but this time I can't help myself. Pharmacyclics was upgraded this morning by TheStreet from a sell to a buy. Keep in mind, the stock has rallied about 400% over the past year and only today did the stock get upped to a buy rating. TheStreet Ratings believes its recent growth in revenue and income is a sustainable trend that investors should buy into.

Now what: I actually feel what could be funnier than the upgrade after a 400% run is the price target that TheStreet Ratings set on the stock -- $25.98. That's right... $25.98; just 3% higher than where the stock is currently trading! This more or less highlights the dangers of being sucked into the day-to-day gyrations that analyst upgrades and downgrades can cause on a stock. My advice is to stick with the same investment thesis you had on Pharmacyclics prior to today's upgrade.

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