Why Housing development finance coproration Ltd share price suddenly down to 603.80?.I bought 2 shares for Rs.6019/- on 1 week ago.Now it is showing as 603.80.Why this huge gap?????

Corporate Action Information for HDFC
Record Date 20-AUG-10 EX – Date 18-AUG-10
Purpose FACE VALUE SPLIT FROM RS.10/- TO RS.2
now in lieu of your 2 shares you will get 10 shares of face value 2
hence the value of your shares are now 6220/- as per nse closing 622/-