It's no secret that HTC has had some issues getting component suppliers to take it seriously after a few bad years. This has led to delays in getting the much-improved HTC One on store shelves. As such, the Taiwanese company has already extended its $100 trade-in program once, and now it's doing so again. You now have almost another full month to take HTC's free money when you buy the One.
The previous cut-off date for buying a One was April 26th, but now you have until May 19th. When you have your new device in hand, register with HTC and send in your old device.