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 MannKind (NASDAQ:MNKD), a clinical-stage biopharmaceutical company focused on developing therapies to treat cancer and diabetes, vaulted higher by as much as 10% on the day after receiving an upgrade from research firm Piper Jaffray.

So what: Before the opening bell, Piper Jaffray upgraded MannKind to neutral from underweight and more than tripled its price target on the company to $6.50 from $2 on the heels of management's confidence that experimental inhaled diabetes drug Afrezza will be approved by the Food and Drug Administration, and based on commentary that the company is already in talks to find a partner for the drug (once approved). As a refresher, Afrezza has been rejected by the FDA once before, and its latest new drug application filing was delayed three months from a PDUFA date of April 15 to July 15.

Now what: As usual, I wouldn't pay too much attention to analyst ratings as they rarely have a meaningful long-term impact on our investment thesis. In addition, these research firms aren't accountable for your investments -- you are! With that being said, Piper Jaffray's price target of $2 looked a bit silly with MannKind trading around $6.50 already, so the upgrade seemed like a logical reactive response. While I, too, feel there's a better than 50-50 chance of approval for Afrezza on or before its July 15 decision date, I still see a number of obstacles which makes its $2.6 billion valuation appear quite frothy. Its ability to successfully launch Afrezza, and its inability thus far to land a partner with its cash pile dwindling are all front-and-center concerns in my book. With that being said, I plan to remain a casual observer on the sidelines until well after the FDA's decision.

MannKind shares soared today, but even it could struggle to keep pace with this top stock over the long run
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Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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