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 little-known Ixia (Nasdaq: XXIA) soared as much as 13%, after the company reported market beating fourth-quarter results last night.

So what: Ixia posted $0.18 per share in adjusted profits on $77.8 million in revenue, a record for the company and a 39% increase over last year’s Q4. Analysts were expecting $0.17 and $74.8 million, respectively. Clearly, this is a growth story in the making.

Now what: But is it a sustainable story, one in which tech investors should take interest? There’s room for debate. On the one hand, Ixia’s technology is useful for testing the equipment behind the new generation of wireless LTE networks now being built by the likes of AT&T (NYSE: T) and Verizon (NYSE: VZ).

On the other hand, Ixia suffered three years of nonexistent growth from 2007 to 2009. Which is the real Ixia? I suspect a lot of that depends on the spending habits of LTE network builders. Rather than buy Ixia shares at current prices, I’d wait to see whether the LTE builders keep spending.