THE Johannesburg Stock Exchange is to close for business on December 30 and 31 to avoid any possible glitches caused by the Y2K bug, the JSE said in a statement Wednesday. It said key personnel would be at work on those two days to assist in the orderly transition of JSE systems to the year 2000. “The decision to close the JSE for business on December 30 and 31 has been taken in the interests of ensuring business continuity into the year 2000,” the JSE said.