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 Fortinet (Nasdaq: FTNT) surged as much as 16% in intraday trading after the data security company reported strong first-quarter earnings and announced a plan to split its stock 2 for 1 in June.

So what: Fortinet is on a roll. Revenue improved 34% to $93.3 million while adjusted earnings more than doubled to $0.17 a share. Analysts had been calling for $86.9 million and $0.14, respectively.

Now what: But it's the cash flow statement where Fortinet's story really gets interesting. Cash from operations nearly doubled, to $40.2 million from $21.8 million in last year's Q1. Gross margin also improved 270 basis points to 74.9%.

Billings, meanwhile, rose 34% and deferred revenue rose 26%, reflective of pent-up demand for its appliances that combine hardware and software to protect wired and wireless networks. Analysts will have a hard time keeping up if these trends continue.

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