Top trader Najarian: Buy this financial

State Street Financial Center building, which houses the company's headquarters, in Boston, Massachusetts.
Brent Lewin | Bloomberg | Getty Images

CNBC "Halftime Report" trader Jon Najarian bought shares of State Street Corp. on Wednesday after spotting unusual activity in the options market.

Najarian is in second place in the CNBC Pro's Model Portfolio competition, up 10 percent on the year, beating the S&P 500, which is up 1 percent.

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