Citibank lowers prime to 15 3/4%

Citibank, the nation's second largest, cut its prime rate to 15 3/4 percent Tuesday, from 16 percent. Morgan Guaranty Trust and First National Bank of Chicago immediately followed. Citibank's move came a day after Continental Illinois National Bank of Chicago lowered its prime even further - to 151/2 percent. But large increases in the nation's money supply and commercial and industrial loans are expected to preclude any immediate sharp downturn in interest rates.