Apple shares briefly topped $600 in early trading on Wall Street on Thursday, a day ahead of the launch of the next-generation iPad. Shares of the Cupertino, California-based gadget-maker hit $600.01 shortly after the ringing of the opening bell at 9:30 am (1330 GMT). Ten minutes later they were trading at $597.00, up 1.26 percent on Wednesday\'s close. Apple shares have gained 57 percent in the past three months. Apple\'s new iPad goes on sale on Friday in the United States and nine other countries including Australia and France. A week later the new iPads will be available in nearly 30 more countries.