NEW YORK, Jan 16 (Reuters) - The U.S. Federal Reserve's balance sheet reached $4 trillion in the latest week as its latest stimulus program aimed to help the economy added more Treasuries and mortgage-backed securities to its holdings, central bank data released on Thursday showed.
On Jan. 15, the Fed's liabilities rose to $4.029 trillion from $3.986 trillion a week earlier.
The Fed's third round of quantitative easing began in late 2011 when its balance sheet was less than $3 trillion.
On Dec. 18, the central bank decided to shrink its monthly purchases of Treasuries and MBS by $10 billion to $75 billion in January.(Reporting by Richard Leong; Editing by Chizu Nomiyama)