Foreign institutional investors (FIIs) were net buyuers of Rs 31.50 crore on July 24, Monday according to data released by Sebi today.While FIIs made gross purchases of Rs 1387 crore, gross sales totalled Rs 1355.50 crore.Mutual funds (MFs) were net buyers of Rs 88.62 crore on Monday. MFs made purchases of Rs 416.63 crore and sales of Rs 328.01 crore.