Foreign institutional investors (FIIs) were net sellers of Rs 307.10 crore on July 18, Tuesday according to data released by Sebi today.While FIIs made gross purchases of Rs 917.40 crore, gross sales totalled Rs 1224.50 crore.Mutual funds (MFs) were net buyers of Rs 141.97 crore on Tuesday. MFs made purchases of Rs 285.91 crore and sales of Rs 143.94 crore.