Pete Najarian, co-founder of OptionMonster

One large options trader is buying calls in Waters Corp. ( WAT), which manufactures and sells lab equipment for chemical analysis.

Options volume on Waters for the last month averages 552 contracts a day, but Tuesday more than 4,000 of the March 40 calls alone were bought by mid-afternoon, according to OptionMonster's tracking systems.

Shares of Waters, whose liquid chromatography products are used in health care, food safety, water quality, and other uses worldwide, closed Tuesday up 5.6% to $33.53. The stock will need to move quite a bit higher for the trade to profit, but then again it was over $40 as recently as early February.
At the time of publication, Najarian has no position in Waters Corp.