City Comptroller John Liu said the Dec. 14 school shooting at Sandy Hook Elementary School in Newtown, Conn., prompted the fund's board of trustees to review the system's investments in the gun industry.
He said the board concluded that divestment would be consistent with the fund's fiduciary standards and overall investment process.
"There is no need to support these companies, whose products can destroy lives and shatter communities in the blink of an eye," Liu said. "Our investment portfolio gains nothing by doing business with these firms, and this is a sound decision that sends an important message about our commitment to addressing the plague of gun violence in every possible way."
Michael Mulgrew, president of the United Federation of Teachers, added, "This is the right thing to do. After the tragedy at Sandy Hook, we as educators had to make sure that guns were not part of our holdings."
Pension funds for teachers and public workers around the country began reconsidering their investments in gun makers after the fatal shootings of 20 first-graders and six educators in Newtown.
The New York City Teachers' Retirement System is the largest pension fund to sell its gun industry holdings so far, Liu said. Its programs affect more than 183,000 members, retirees and others, according to figures from its 2011 annual report.
The fund had a total of $13.5 million invested in five gun makers including Smith & Wesson Holding Corp. and Sturm, Ruger & Co.