Pfizer (PFE) was Smart Insider's stock pick of the week after Chief Executive and Chair Albert Bourla bought 38,000 shares for $1 million at $26.34 apiece on Aug. 12.

Bourla, who has been with Pfizer since 1993 and has served as CEO since January 2020, increased his holding by 10% to $11.6 million with his first reported purchase, Smart Insider said in a Tuesday note.

His recent insider activity had mainly involved exercising an option near expiration and surrendering shares to cover the required amount, according to the note.

Smart Insider ranked Pfizer +N, or notable & positive signal, a week earlier after directors Mortimer Buckley and Ronald Blaylock each bought about $1 million of shares, the firm said.

Smart Insider said the three purchases are "confident" buying in a stock that has remained in a narrow trading range for 18 months.

Smart Insider upgraded Pfizer to +1, indicating a strong positive signal.