Najarian buys grocery stock on unusual activity

File photo: Customers shop for produce at a Cub Foods, owned by Supervalu, in Crystal, Minnesota.
Ariana Lindquist | Bloomberg | Getty Images

CNBC "Halftime Report" trader Jon Najarian bought shares of Supervalu, the grocery store operator and distributor, on Monday after spotting unusual activity in the options market.

Najarian is one of the top traders in CNBC Pro's Model Portfolio competition, up 8.6 percent on the year, beating the S&P 500, which is down 2 percent.

Here is what Najarian sees and why he thinks the stock can rally from here...