Foreign institutional investors (FIIs) were net buyers of Rs 555 crore on September 27, Wednesday according to data released by Sebi today.While FIIs made gross purchases of Rs 2090.80 crore, gross sales totalled Rs 1535.80 crore.Mutual funds (MFs) were net sellers of Rs 115.50 crore on Wednesday. MFs made purchases of Rs 484.11 crore and sales of Rs 599.61 crore.