The number on the cover of Eos Energy Enterprises’ June 30, 2026 prospectus supplement is $74,999,997.95 — call it $75.0 million — and the form it came from is a 424B5, a takedown off the company’s existing shelf. That is the headline. The more revealing line is three pages in, under use of proceeds, where the zinc-battery maker tells you the cash is not staying with Eos at all. It is being routed, almost dollar for dollar, into a joint venture. Read the use-of-proceeds line, not the press headline, and this stops being a garden-variety dilution story and becomes a structuring story.

Start with the mechanics, because they are unusually specific for a raise this size. Eos is selling 13,683,634 shares of common stock and 6,004,378 warrants — each share sold together with 0.4388 of an accompanying warrant — in a registered direct offering to a limited number of purchasers, not a broadly marketed underwritten deal. The warrants carry an exercise price of $5.481 per share, the same figure as the per-unit offering price.

“We are offering 13,683,634 shares of our common stock, par value $0.0001 per share, and 6,004,378 warrants, each warrant to purchase one share of common stock at an exercise price of $5.481 per share (the “Warrants”), in a registered direct offering to a limited number of purchasers pursuant to this prospectus supplement and the accompanying prospectus.”— Eos Energy Enterprises, Inc., Prospectus Supplement (Form 424B5), filed June 30, 2026, SEC EDGAR

Where the cash actually goes

Here is where the discipline matters: report the use of proceeds as the filing states it, not as a boilerplate “general corporate purposes” line. Eos says it plans to enter into a JV Agreement establishing an entity called Frontier as a joint venture among Eos, CCM Frontier JV Holdco (an affiliate of Cerberus Capital Management) and HBC. Per the filing, “we will contribute the net proceeds of this offering to Frontier in consideration for a number of Class B Units of Frontier at a price of $1.00 per unit.” In the summary term sheet the same intent is stated flatly: the proceeds are “to acquire Class B Units of Frontier at a price of $1.00 per Class B Unit.”

So the $75 million round-trips through Eos into a Cerberus-anchored vehicle. That is not a criticism — it is a structure, and structures have consequences worth naming. The equity issued here dilutes Eos shareholders at the parent level; the asset received in exchange is a block of Class B Units in a JV Eos does not wholly own. Whether that trade builds or erodes value depends on Frontier’s terms, which sit outside this document. What the 424B5 does confirm is that the parent’s share count grows now, in exchange for a JV interest whose economics the filing does not fully lay out here.

The warrant overhang is bigger than the raise

The 6,004,378 warrants attached to this offering are the small part of the warrant story. Concurrent with the JV, Eos says it will grant 20,017,772 warrants to CCM (the “CCM Warrants”) and 10,008,886 warrants to HBC (the “HBC Warrants”), each exercisable for one share at $5.481, as partial consideration for CCM’s and HBC’s investments into Frontier. Add it up and roughly 36.0 million shares of potential issuance sit behind this transaction once you count the offering warrants and the two counterparty grants — well more than the 13.7 million shares being sold today. The CCM and HBC warrants are redeemable by Eos on the same terms as the offering warrants, and the offering warrants themselves carry a beneficial-ownership cap that blocks exercise above a 4.9% or 9.8% threshold, at the holder’s election.

For scale on the dilution question: Eos reports 339,459,021 shares of common stock outstanding as of March 31, 2026. The 13,683,634 shares sold in this offering are about 4% of that base before any warrant exercise. Layer in the full warrant stack — offering, CCM and HBC — and the potential share creation is materially larger, though staged over time and gated by the exercise price and the ownership caps. That is the number-forward way to hold both facts at once: the immediate common-share dilution is modest; the embedded warrant overhang is not.

The conditions that could still unwind it

A raise is only as firm as its closing conditions, and this one carries two that are worth flagging. Eos states it has entered into an amendment to its Credit Agreement — the June 21, 2024 facility with CCM Denali Debt Holdings, LP — and a consent under its DOE Loan Facility, both to permit the issuance of the common stock and warrants. The effectiveness of that amendment and waiver, the company says, “is subject to certain conditions, some of which are outside of our control,” and it warns it cannot assure investors the offering will be consummated on the stated terms, if at all. The DOE relationship traces to a Loan Guarantee Agreement dated November 26, 2024 with the U.S. Department of Energy, and future funding under it is itself listed among the risk factors.

That is the reconciled picture from the filing, not the deck. Eos, which describes itself as an American company making zinc-based battery energy storage systems for utility-scale, microgrid and commercial-and-industrial long-duration applications, is raising $75.0 million in a registered direct deal whose proceeds are pledged to a joint venture, whose closing hinges on a lender amendment and a DOE consent, and whose warrant structure could roughly triple the share count created versus the shares sold today. None of that is a verdict on the equity — batteryfolio does not issue those. It is a map of what the primary document says, and where a reader should look next: the JV Agreement’s terms and Frontier’s capital structure, neither of which this prospectus supplement fully discloses.

The trade to watch is the one this filing sets up but does not resolve: common equity out at the parent, Class B JV units in at $1.00 each, and a Cerberus affiliate on both sides of the structure. Reconcile it to the JV Agreement when it lands.