Has momentum stalled for Plug Power (PLUG)? 2021 is proving a bit of a come down for this previously high-flying new energy stock. To wit, since peaking at $70.3 in mid-January, the share price has retreated by a hefty 64%. The hydrogen fuel cell maker’s pullback has been part of a wider trend as growth stocks have taken a breather, but investors have also found reasons for concern due to a more specific issue.