Activist investor ValueAct has reportedly amassed a $1.2 billion stake in Citigroup

Larry French/AP

• ValueAct Capital has taken a $1.2 billion stake in Citigroup, according to The Wall Street Journal.
• The activist investor supports CEO Michael Corbat and reportedly isn't pushing for significant changes.

Activist investor ValueAct Capital has amassed a $1.2 billion stake in Citigroup, according to The Wall Street Journal.

ValueAct took an $80 million stake in the bank in December and has since built it up to $1.2 billion, which is roughly 7% of Citi's $175 billion market capitalization.

The activist isn't looking to shake up management and supports CEO Michael Corbat, according to the WSJ. It is, however, pushing for an increase in cash returned to shareholders.

"We have been having constructive conversations with ValueAct and welcome them as investors," a Citi spokeswoman told the WSJ.

Citi stock is up 1.8% in after hours trading.