Bill Ackman expects U.S. President-elect Donald Trump to remove Fannie Mae and Freddie Mac from conservatorship, potentially making them private companies again, the billionaire investor said Monday.

Shares of Fannie Mae climbed 18.4%, while those of Freddie Mac rose 18% following Ackman's post on social media platform X.

According to Ackman's post, Fannie Mae and Freddie Mac may emerge from conservatorship in the next two years, potentially leading to their public listing around 2026.

Fannie and Freddie, which operate as for-profit corporations with private shareholders, were created by Congress with the mission of expanding the national home lending market by buying home loans from private lenders and repackaging them as mortgage-backed securities.

When the housing market collapsed in 2008, the companies suffered overwhelming losses. To avoid catastrophic effects for the U.S. economy, they were placed in conservatorship under the newly created Federal Housing Finance Agency.