GWH vs STEM: Which Is the Better Buy in 2026?
Last updated August 2026
Short answer
STEM is the larger of the two ($48.37M market cap): the incumbent the market prices for continued execution (-0.93x forward earnings, beta 1.46). GWH is the smaller challenger ($21.95M), priced similarly on forward earnings (-0.95x): more room to run, but more to prove. The real question is which set of drivers you believe, and whether owning one (or both) leaves you over-concentrated.
GWH vs STEM: the tie-breaker metrics
Same yardstick, side by side (as of August 2026). Valuation lined up like this is most meaningful for two names in the same corner of the market, which these are. Figures are approximate; verify before investing.
| Metric | GWH | STEM | What it tells you |
|---|---|---|---|
| Market cap | $21.95M | $48.37M | Size. The larger name is the incumbent; the smaller has more room to grow and more to prove. |
| Forward P/E | -0.95 | -0.93 | Valuation on next year's expected earnings, the same yardstick for both. Lower is cheaper for that growth; higher means the market is paying up. |
| Beta | 1.41 | 1.46 | Volatility vs the market. Above 1 swings harder than the index; below 1 is steadier. Higher beta means bigger drawdowns to hold through. |
| Price vs 52-week range | 1% of range | 2% of range | Where today's price sits between the 52-week low and high. Near the high is momentum with less margin of safety; near the low is out of favor or a discount, depending on why. |
Before you buy: how GWH and STEM affect your concentration
The metrics above tell you which is the marginally better business. The bigger risk for most people is not picking the slightly worse stock, it is over-concentrating. GWH and STEM share themes, so owning both, or adding either to what you already hold, can quietly push a large share of your portfolio into one bet.
This is the part a generic comparison page cannot answer, because it depends on what you own. Connect your brokerage and Walnut shows your real, combined GWH and STEM exposure, flags overlap with your existing positions, and tells you if adding one would tip you past a concentration you are comfortable with, read-only by default, with your login staying at your broker. Walnut is not an investment adviser.
What does ESS Tech (GWH) do?
ESS Tech, Inc. designs and builds long-duration energy storage systems intended to hold electricity for many hours, longer than typical lithium-ion batteries, to help balance grids with more renewable power. Its core technology has been the iron flow battery, which uses an electrolyte of iron, salt, and water and is pitched as safe, low-cost over a long life, and free of scarce or flammable materials. The company went public via SPAC in 2021 and manufactures in Wilsonville, Oregon. In 2026 ESS is in a difficult transition: it has been reallocating resources toward sodium-ion battery systems after early customer interest, acquired the intellectual property and assets of Germany's VoltStorage to combine complementary iron-salt technologies, and is streamlining Wilsonville operations to cut expenses and slow cash burn while still advancing its flow-battery work.
What does Stem (STEM) do?
Stem, Inc. is a clean-energy technology company that provides AI-driven software and services for battery energy storage and solar assets. Its platforms include PowerTrack (the enterprise optimization and monitoring platform formerly branded Athena) and PowerBidder Pro, an AI-enabled tool that helps asset owners and traders bid storage into wholesale power markets such as ERCOT. The company earns money from software subscriptions, managed and edge-device services, and, historically, hardware resale. Beginning in late 2024, Stem announced a strategic realignment to move away from reliance on low-margin hardware toward a software- and services-led model, aiming to lift gross margins, build recurring revenue, and grow annual recurring revenue (ARR).
GWH vs STEM: how do they differ?
Both fit overlapping themes, but they are not interchangeable. The useful comparison is which set of drivers and risks you want exposure to.
- GWH drivers: Long-duration storage market opportunity; Pivot to sodium-ion and a combined platform.
- STEM drivers: Software and SaaS transition; Growth in energy storage markets.
Which fits which kind of investor
A faster-growing, richer-valued name usually swings harder, so it suits a longer horizon and a higher tolerance for volatility; a steadier, more cash-generative business suits a more conservative or income-minded investor. The honest test is which set of risks you could hold through a drawdown: The risks here are existential, not incremental. For STEM, the central risks are that Stem is a small-cap turnaround with a modest revenue base, a history of losses, and a debt load that has pressured its balance sheet, and the software transition is still unproven at scale.
GWH or STEM: which should you pick?
Growth-minded investors who believe the theme has years to run tend to accept the richer multiple for more upside; value-minded investors lean toward the cheaper forward earnings and steadier profile. Pick GWH if you believe its drivers more; STEM if you believe its. Many investors hold both, but since they share themes, that is a concentrated bet, not diversification. Decide deliberately and check overlap. For the full detail, see the GWH and STEM guides.
GWH vs STEM: the full fundamentals
GWH. Figures are approximate, tied to the asOf date, and change quickly for a distressed company, so verify the latest 10-Q/8-K filings, cash balance, and NYSE listing status before acting. Traditional valuation multiples are of limited use here: with almost no revenue and ongoing losses, the equity is best understood as a speculative option on a successful turnaround and financing rather than a claim on current earnings. A reverse stock split, if executed, would change the share count and per-share price without changing the underlying business, so read any such action carefully.
STEM. Figures are approximate and tied to the asOf date; verify live numbers before acting. Stem is a small-cap turnaround mid-pivot from hardware to software, so results can be lumpy, guidance ranges are wide, and reported GAAP results differ meaningfully from adjusted EBITDA. The 1-for-20 reverse split in June 2025 also changed the share count and per-share figures, so be careful comparing pre- and post-split numbers. Confirm the latest revenue, ARR, cash, and debt directly from filings before drawing conclusions.
Headline figures (approximate, Jul 2026): GWH shows revenue trajectory Fell from ~$6.3M (2024) to ~$1.6M (2025); Q1 2026 revenue ~$128K as products transition (verify live), liquidity / cash ~$21.5M total liquidity at Q1 2026, declining toward the mid-teens of millions by late spring 2026, going concern Management has disclosed substantial doubt about the ability to continue as a going concern, listing status NYSE June 2026 deficiency for trading below the $1.00 minimum; six-month compliance window; reverse split under consideration; STEM shows q1 2026 revenue (software, services, edge hardware) ~$29 million, up modestly year over year; PowerTrack software revenue up ~16%, fy2026 revenue guidance Roughly $140 million to $190 million (a wide range signaling uncertainty), adjusted ebitda Several consecutive positive quarters; FY2026 guided to modest positive adjusted EBITDA (roughly $10 million to $15 million), year-end arr (guided) Mid-$60-million range (~$65 million to $70 million).
The bottom line: GWH vs STEM
GWH and STEM are related but distinct: same themes, different businesses and risks. Neither wins in the abstract; the right pick is whichever thesis you actually believe, sized so you are not over-concentrated in one theme. Walnut can show your combined GWH and STEM exposure against your real portfolio. It is not an investment adviser.
Wondering how GWH or STEM fits the portfolio you already own? Walnut is an AI investing app that connects your brokerage read-only and answers questions like that about your actual holdings: overlap, concentration, and how each position tracks the S&P 500. Compare the best AI portfolio analyzers or see the best AI investing apps in 2026.
Investing in ESS Tech with AI
Connect the broker you already use and ask Walnut's AI how GWH fits what you actually hold: whether you own it already through a fund, what it would do to your concentration, and how it has tracked the S&P 500. Read-only by default, and you approve anything before it reaches your broker.
FAQ
What is the difference between GWH and STEM?
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ESS Tech, Inc. Stem, Inc. They show up together because they share investment themes, but they are different businesses, so the better fit depends on which thesis you are expressing.
Is GWH or STEM the better stock?
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Neither is universally better. STEM is the larger incumbent; GWH is the smaller challenger and looks cheaper on forward earnings. Walnut is informational, not investment advice. Compare what each does, the tie-breaker metrics above, and the risks, then decide which fits your thesis and what you already own.
Which is cheaper, GWH or STEM?
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On forward P/E (as of August 2026), GWH trades at -0.95x and STEM at -0.93x, so GWH is the cheaper of the two on next year's expected earnings. A lower multiple is not automatically the better buy: a richer valuation can be justified by faster growth, and a lower one can reflect real risk. Weigh the multiple against how fast each business is compounding.
Should you own both GWH and STEM?
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Because they share themes, owning both concentrates you in that theme. That can be intentional (a focused bet) or accidental (less diversification than it looks). Walnut can show your combined exposure across both, and whether adding either over-concentrates you, before you buy.
What are the risks of GWH vs STEM?
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GWH: The risks here are existential, not incremental. ESS has disclosed substantial doubt about its ability to continue as a going concern, revenue has collapsed to a trickle, and liquidity of roughly the mid-teens of millions is being consumed quickly, so the company may need to raise capital on terms that could heavily dilute existing shareholders or, if financing is unavailable, face a far worse outcome. The stock trades below the NYSE $1.00 minimum, putting it on a compliance clock that could lead to a reverse stock split or, in a bad case, delisting; its warrants were already slated for delisting. The mid-stream pivot from iron flow to sodium-ion and a combined platform adds technology and execution risk on top of a business that has not yet reached commercial scale. Third-party estimates have flagged an elevated probability of bankruptcy and a deeply negative Altman Z-score. This is a speculative micro-cap where a total loss is a realistic outcome; anyone considering it should verify the latest cash balance, filings, and listing status and size any position accordingly. STEM: The central risks are that Stem is a small-cap turnaround with a modest revenue base, a history of losses, and a debt load that has pressured its balance sheet, and the software transition is still unproven at scale. The June 2025 reverse split to keep its NYSE listing underscores past share-price and compliance pressure that could recur if execution disappoints. Revenue can be lumpy as the company shifts away from hardware, and full-year guidance spans a wide range, signaling uncertainty. Competition is intense from larger, better-capitalized players in energy storage and management software. Growth also depends on renewable and storage deployment, which is sensitive to interest rates, policy, tax-credit changes, and utility budgets, all outside the company's control. Continued cash burn could force dilution or refinancing on unfavorable terms.
Walnut is informational, not investment advice. This page is descriptive and not a recommendation to buy or sell GWH or STEM; figures are approximate and dated (as of August 2026). Verify current data before investing.