Activist investor ValueAct Capital Partners has built a roughly $1.2bn stake in Citigroup, a bet that the giant bank’s strength as a service provider to corporations will enable it to thrive in the post-crisis era and make up ground its shares have lost in recent years.

ValueAct, which has built the position over the past four to five months, continues to boost it “opportunistically,” according to a letter to its own investors reviewed by The Wall Street Journal. The stake amounts to about 0.7% of Citi, which has a market value of $175bn.