Foreign institutional investors (FIIs) were net buyers of Rs 236 crore on September 20, Wednesday according to data released by Sebi today.While FIIs made gross purchases of Rs 1377.10 crore, gross sales totalled Rs 1141.10 crore.Mutual funds (MFs) were net sellers of Rs 269.32 crore on Wednesday. MFs made purchases of Rs 320.33 crore and sales of Rs 589.65 crore.