By Koh Gui Qing NEW YORK (Reuters) -U.S. stocks extended their rally on Wednesday in volatile trade and Treasury yields rose after the Federal Reserve raised interest rates by three-fourths of a percentage point, the biggest increase since 1994, as it sought to tamper surging inflation. Investors seemed relieved that the U.S. central bank had met the market’s expectations with the rate hike, and appeared for now to be comfortable with the Fed’s projection that the economy is set to slow in the next two years. By 2:42 p.m. EDT (1842 GMT), U.S. shares had extended gains after an initial pullback…