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What: Shares of Guidance Software (NASDAQ: GUID) have plunged today by as much as 25%, after the company reported earnings.

So what: Revenue in the fourth quarter added up to $36.2 million, with non-GAAP earnings per share of $0.17. The bottom line result was slightly better than expected, which partially offset the disappointment from the top line miss, as investors were expecting $37.2 million in sales.

Now what: Guidance's guidance left a little to be desired, with full year revenue expected to be in the range of $144 million to $148 million, the midpoint of which is short of the $147.4 million consensus estimate. Non-GAAP earnings per share should be $0.25 to $0.30, which is well below the $0.50 per share in adjusted profit that analysts thought was in order.

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