This hydrogen stock still remains below its IPO price 25 years after its public debut.Plug Power (PLUG 4.25%) was considered a promising play on the nascent hydrogen fuel cell market when it went public in 1999. But today, it trades nearly 99% below its initial public offering (IPO) price. Many of its investors retreated after the dot-com bubble burst in 2000; its growth cooled off; and it struggled with accounting issues from 2018 to 2020.That was a devastating drawdown for Plug's long-term investors, but ...