Plug Power Stock Keeps Rolling. Is It Time to Buy?

Plug Power (PLUG 4.49%) stock just keeps plugging ahead. It jumped as much as 15.5% today. Even though it pared those gains to 4.7% as of 12:15 p.m. ET, shares of the hydrogen fuel company are still about 35% higher over the past week.Its stock has struggled over the last year, along with the stocks of other renewable energy companies. Plug's shares, though, have been hit particularly hard, as its cash reserves have been dwindling, and it announced last month that it reached an agreement with an investor to ...