Updated from 11:42 a.m. EDT

Taser ( TASR) fell in heavy volume Monday as nervousness grew ahead of a report about the stun-gun maker on CBS News. The network's Web site is teasing a story that will purportedly show a "fatal accident caught on tape" involving Taser. While no other details were released, the guns have been the subject of a spate of recent media skepticism lately, including a New York Times story last week suggesting that the company hasn't conducted meaningful safety testing. Taser traded down $4.29, or 14.5%, to $25.23 on volume of about 14 million shares.

Shares of PetMed Express ( PETS) were among the Nasdaq's losers Monday after the company posted weaker-than-expected first-quarter earnings. The pet pharmacy company earned 8 cents a share on sales of $35.3 million. Analysts polled by Thomson First Call had expected it to earn 11 cents a share. A year ago it earned 6 cents a share on sales of $30.4 million. Shares of PetMed Express traded down $2.07, or 29.7%, to $4.90.

Alderwoods Group ( AWGI) fell after it reported weaker-than-expected second-quarter earnings. Excluding items, the funeral home and cemetery operator earned 7 cents a share on sales of $164.1 million. Analysts had expected it to earn 11 cents a share. A year ago it reported a loss of 5 cents a share on sales of $166.5 million. Shares of Alderwoods Group traded down $1.75, or 15.2%, to $9.75.

Shares of Tyson Foods ( TSN) slipped after the company reported strong third-quarter financial results but warned that full-year earnings would fall short of expectations. Excluding one-time items, the meat company earned 42 cents a share on sales of $6.6 billion. Analysts had expected it to earn 36 cents a share on sales of $6.53 billion. Looking ahead, it now expects to report a profit of $1.20 to $1.30 a share for the full year. Analysts, however, were looking for it to earn $1.41 a share. Shares of Tyson Foods traded down $1.47, or 7.4%, to $18.48.

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