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 staff services company Corporate Resource Services (NASDAQ: CRRS) jumped as much as 20% in early trading after announcing guidance. Shares fell in late trading but are still up 7% on the day.

So what: Management said that earnings to be released on Nov. 13 will show a 17% increase in revenue from a year ago and a 50% sequential jump in EBITDA margins. This past month was the most profitable in the company's history and bottom-line margins are expected to be abnormally high.  

Now what: This was positive guidance, but we'll have to wait a month and a half to get the final numbers. Also consider that higher net margins don't mean much when you're barely profitable to begin with. I'd like to see longer-running strong margins than just one quarter before buying in, so see what guidance for next quarter looks like in November.

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