Stanley Fischer is stepping down as vice chairman of the Federal Reserve, creating another opening at the central bank for President Donald Trump to fill.

In a letter to Trump on Wednesday, Fischer cited "personal reasons" and said the resignation will take effect Oct. 13, two days before his 74th birthday.

"It has been a great privilege to serve on the Federal Reserve Board and, most especially, to work alongside Chair [Janet] Yellen as well as many other dedicated and talented men and women throughout the Federal Reserve system," Fischer wrote.

The resignation of Fischer, whose term was set to expire on June 12, 2018, creates yet another opening at a critical time for the Fed. The central bank is set to begin unwinding the $4.5 trillion balance sheet of bonds it built up during its economic stimulus efforts and is trying to normalize interest rates after keeping its benchmark rate near zero for seven years.

Trump already has nominated Randal Quarles to one vacancy and now will have at least two more. In addition, Yellen's term ends in February.

Though Fischer did not elaborate on his reasons for leaving, he did talk up the Fed's accomplishments during his tenure.