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 Affymetrix (NASDAQ:AFFX)advanced as much as 11% after the maker of life science tools and molecular diagnostic products announced preliminary fourth-quarter revenue guidance and received a price target upgrade from a Wall Street firm.

So what: Affymetrix said in an early morning press release that it anticipates reporting fourth-quarter revenue of $91 million, which includes a one-time payment of $5.3 million from a diagnostic partner. By comparison, Wall Street had anticipated Affymetrix would report just $82.6 million in revenue. For the full year, Affymetrix now anticipates revenue totaling $329 million. In response to the stronger-than-expected revenue projections, Maxim Group upped its price target on the company to $11 from $9.

Now what: Steady as she goes for Affymetrix, which has done a good job of reducing debt and returning to profitability (no matter how nominal) in fiscal 2013. We know that Affymetrix can reduce expenses and use its leanness to deliver profits; the big question moving forward is whether the company can organically grow product orders. Based on current estimates on Yahoo! Finance, and factoring in today's upside announcement, we're looking at flat year-over-year sales in 2014. Cost-cutting will only drive a company so high before shareholders get impatient. Tack on the fact that the federal health care spending budget is likely to contract and you have enough reasons to be somewhat skeptical of the magnitude of this latest rally in Affymetrix.

Fool contributor 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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