LONDON -- A share price plunge of 46% enticed the private clients of stockbroker TD Direct Investing to load up on May Gurney (LSE: MAYG.L) this morning. The infrastructure services firm was the sixth-most popular pick between the market's opening and 12 noon.

The reason for such a precipitous plunge? A profit warning and the abrupt departure of the company's chief executive. It's all rather different, in short, from the mood music just three months ago, when the firm thought public-sector expenditure cuts were actually going to deliver a boost to the bottom line.

For the year ending March 31, May Gurney had seen underlying pre-tax profits climb 17% to 28.4 million pounds -- ahead of forecasts. Today, announcing the closure of some activities and severe difficulties with others, it says that it expects to "significantly underperform" in the current year. Nonetheless, despite the 46% slump in the share price, some investors evidently rate the stock a buy.

Another business that knows a bit about significant underperformance is oil giant BP (LSE: BP.L), still suffering from the Gulf of Mexico disaster of 2010. With last month's hurricane now blowing fresh deposits of oil onto Gulf shorelines, the U.S. Justice Department has accused BP of "gross negligence and willful misconduct" in the run-up to the disaster as it gears up for a court case.

The whole thing could drag on for years, and BP continues to suffer the fall-out of its long-running dispute with its partners in its Russian oil interests. But trading at 423 pence, there's obviously enough interest in the shares to make the company the ninth-most popular buy among TD Direct Investing's private clients between the market's opening and 12 noon.

Elsewhere, bargain seekers were clearly running the rule over specialist high-tech plastics company Carclo (LSE: CAR.L), which, after falling 6%, was the tenth-most popular buy among TD Direct Investing's private clients between the market's opening and 12 noon.

Why the drop? An RNS explaining that an order for smartphone touch sensors had been delayed, pending the resolution of "product design issues."

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