Foreign institutional investors (FIIs) were net buyers of Rs 321.30 crore on July 20, Thursday according to data released by Sebi today.While FIIs made gross purchases of Rs 1433.90 crore, gross sales totalled Rs 1112.60 crore.Mutual funds (MFs) were net sellers of Rs 80.13 crore on Thursday. MFs made purchases of Rs 440.81 crore and sales of Rs 520.94 crore.