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 biopharmaceutical company Questcor Pharmaceuticals (NASDAQ: QCOR) jumped as much as 11% in intraday trading Tuesday following positive analyst comments from Jefferies, as well as an upgrade from the research firm.

So what: The covering analyst at Jefferies, Biren Amin, bumped up his rating on the company to "buy" from "hold" while boosting his price target to $28. The reasoning behind the move, according to Amin, is that investors have become too pessimistic with regard to Questcor's leading -- but expensive -- drug, Acthar, being dropped by insurers. Currently, only Aetna (AET) has said it was dropping coverage on all but one indication of the drug. In addition, Amin points out that Medicaid will be reducing the reimbursement rate for Acthar, which should net Questcor more in revenue since it had been forced to pay full rebates to state Medicaid programs that purchased the drug.

Now what: Eight simple words here are all you need to know: The U.S. government is probing its marketing practices. With that dark cloud hanging over Questcor, none of this white noise matters very much. Analyst upgrades and downgrades tend to be very short-term movers of a company to begin with and usually have very little bearing on the investment thesis of a stock.

What matters is that previous government probes resulted in hefty fines of $2.2 billion to Johnson & Johnson (JNJ -0.85%) and $780 million to Amgen (AMGN -0.87%), and could result in a whopper of a fine for Questcor if its deemed that it improperly priced its Acthar at $33,000 per treatment across all indications while relying on the protection of its orphan-drug status. To me, these are risks that can easily be avoided by avoiding the stock altogether.

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