Form Energy, the long-duration battery storage company building iron-air batteries for grid-scale energy storage, closed a $750M Series G on August 12, 2026 at a $2.5B post-money valuation. That's down from $3.5B at its 2024 round — the pre-money valuation fell from roughly $3B to roughly $1.75B, a genuine down round rather than a slower step-up.
The numbers
A down round changes the math for existing option holders in a specific way: your strike price was set relative to the fair value at your grant date, and if that fair value has now fallen below your strike, your options are underwater — worth exercising only if you believe the company will recover past your strike price before you'd need to sell. The size of the new raise ($750M) is large relative to the new valuation, which also means meaningful new dilution layered on top of the lower headline number.
What changed
This down round reflects a broader reset across climate and battery-storage startups in 2026, as capital costs remain elevated and some later-stage climate-tech companies that raised at peak 2021–2022 valuations are now finding growth capital only at lower marks. It's not necessarily a signal that Form Energy's underlying technology or commercial progress has stalled — grid-scale storage demand remains strong — but it does mean the market is pricing execution risk and capital intensity more conservatively than it did two years ago.
What this means for employees
Companies going through a down round frequently follow up with an option repricing (lowering the strike price on existing underwater grants to the new, lower fair value) or refresh grants at the new price to keep compensation packages competitive — ask your equity administration team directly whether either is planned. Also pay attention to the terms of the new preferred stock: down rounds are often accompanied by senior liquidation preferences or multiple-liquidation-preference structures that sit ahead of common stock in a payout waterfall, which can mean option holders see meaningfully less than the headline valuation implies even in a decent exit.
If you're holding Form Energy options granted before this Series G, check your strike price against the new $2.5B valuation and ask whether a repricing or refresh grant is on the table — then run the calculator with the updated numbers to see where you actually stand.