Vehicles can now navigate with GPS fully jammed. The stock behind the tech is falling for a different reason.

On September 3, a moving vehicle lost its GPS signal completely — every satellite in the constellation jammed out — and it still knew exactly where it was, and it stayed connected to the outside world. That was not a lab simulation. It was a live test run for the U.S. military, and two companies built the system that let the vehicle do it: NAVSYS Corporation and ALL.SPACE.

The reason the headline matters to you is more specific than "the Army is betting on AI navigation." Only one of those two companies can actually be bought on a stock exchange, and it got into this business by buying the other one — not by inventing the jamming-proof trick itself. That is where the capability story ends and the investment question begins.

What the demo actually proved, and what it did not

The system did not need any new satellites. GPS — and most of the backups being planned to replace it — ride on one particular, easily overwhelmed band of signal. This one sidestepped that band entirely. Instead, it read the signals that are already flooding to Earth from ordinary commercial communications satellites — the Ku- and Ka-band transmissions that carry television and internet — and used them to figure out position and timing. ALL.SPACE's Hydra terminal kept the vehicle talking to those satellites on the move, and NAVSYS's software harvested them to compute a location.

That architecture is the whole point, and it is why the result is real and near-term. Because it leans on satellites that already exist, it can be fielded without a multi-year, multi-billion-dollar constellation build-out. NAVSYS makes that the crux of its own argument: it says privately funded navigation constellations are not economical on their own, and a software layer that piggybacks on the commercial hardware already in orbit is the fieldable alternative.

But hold onto this boundary. It was a demonstration. There is no disclosed contract value attached to it, no units in production, and no revenue line where you can see it yet. It is a capability that now exists. It is not, yet, a business.

The only public piece is York Space Systems — and the tech is the least of its story

The investable company is York Space Systems (NYSE: YSS). In late January it went public, selling shares at $34, and in July it closed a roughly $355 million acquisition of ALL.SPACE, making the terminal maker a wholly owned subsidiary. So the GPS-jamming capability is, as of this month, part of the YSS portfolio. That is a genuine differentiator: it lets YSS sell a combined communications-and-positioning bundle for contested environments, rather than a satellite on its own.

But the demo is not what the stock is being paid for — or punished for. YSS is primarily a builder of satellites for the U.S. government, and its near-term fortunes turn on delivering one big program: the Transport Layer satellites for the Proliferated Warfighter Space Architecture. Its 2025 revenue jumped 52% to $386 million, and it had guided 2026 to roughly $570 million — another ~50% of growth, driven by that government work.

Then, in mid-August, it cut 2026 guidance to $375–405 million. That is not a trim. Measured against 2025, the new number is roughly flat — the growth story walked all the way back to zero. The company pointed to timing delays on government contracts and supply-chain constraints. Second-quarter revenue of $92.5 million was up just 10%, and the per-share loss came in wider than expected for the second straight report. The stock fell hard around the print and has kept sliding since, now sitting about 76% below its IPO price.

Where that leaves you

The navigation breakthrough is real operating progress, and YSS now owns a piece of it. As a way to stand out in a crowded space market, that is worth something. But a capability at the demonstration stage does not move the multiple. The number that decides this stock is whether those delayed government satellites actually ship and turn into revenue — and the evidence currently points the wrong way: a price down three-quarters from the offering, and a business still spending more than it earns, carried on the cash it raised rather than on its own cash flow.

The longer argument — that the U.S. military will keep paying to stop depending on a signal any adversary can switch off with a handheld device — is intact. That does not answer the question that actually decides where you put money: whether the return over the next year or two is as good as the other uses of the same capital. Right now the demo proves what YSS can do. It has not yet shown that what it is doing is on schedule, or that the price leaves you anywhere to run.