Hong Kong stocks suffered their biggest one-day drop since October 2008 on Wednesday, dragged down by another tumble on mainland exchanges, as well as bearish overseas markets amid fresh doubts that Greece can reach a bailout deal with Europe. The Hang Seng index plunged 5.8 percent to end at 23,516.56, the lowest close since January. The China Enterprises Index lost 6.1 percent in the biggest fall since September 2011, to 11,107.30 points, the lowest close since December.