Plug Power Inc (NASDAQ:PLUG) shares dropped by 6.6% to $3.90 following a downgrade by Citigroup from Buy to Neutral and a price target reduction from $12.5 to $5. The downgrade comes after last week's Q3 financial results, which included a 'going concern' warning due to a substantial deficit, cash flow issues, and predicted losses of $3.8 billion. The company's poor performance was attributed to challenges in the hydrogen network, leading to revenue shortfalls and a net loss of 47 cents per share.