The Electro Optic Systems Holdings Ltd (ASX: EOS) share price has been on an extraordinary run.
Even after falling about 4% today (at the time of writing), the defence technology company's shares remain near all-time highs. The stock has surged almost 80% over the past month and an astonishing 800% over the past year.
So after such a dramatic rally, the obvious question for investors is: Should they buy, hold, or sell?
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What's driving the momentum?
Part of the recent surge followed last week's announcement that EOS had secured US$45 million in new counter-drone orders, including a major order from a Middle Eastern customer for its Slinger Remote Weapon System.
More broadly, the company said the ongoing conflict in the Middle East has sparked growing interest from governments in counter-drone systems, including its cannon-based Slinger platform and APOLLO laser technology.
Importantly, EOS' order book has also expanded rapidly. At the last count, the company had more than $400 million in orders, up 238% from 2024.
Given that EOS generated $128 million in revenue in 2025, that backlog suggests the company has multiple years of potential revenue already contracted.
But does the valuation make sense?
EOS now has a market capitalisation north of $2 billion, despite reporting a 2025 NPAT of $17.5 million, and even that profit figure includes a $91 million gain from the sale of discontinued operations, meaning the underlying business is not yet meaningfully profitable.
In other words, the market is clearly pricing in significant growth expectations to materialise, and investors are valuing EOS based on its expected future growth rather than current earnings.
If the company successfully converts its rapidly expanding order book into sustained revenue growth (and ultimately strong cash flow with healthy margins), then today's valuation may prove justified.
But if contract execution or margins disappoint, expectations could reset quickly.
Expect volatility
Investors should, however, expect volatility, even if EOS' operations continue to improve. A shift in sentiment (perhaps as a result of headlines of a peace deal in the Middle East) could result in the share price cooling off, and investors have already experienced this before.
The stock has fallen around 40% twice during previous pullbacks, including in October 2025 and earlier this year, and so that's a risk that investors need to be mindful of.
Buy, hold, or sell?
On balance, for new investors, chasing a stock after a 1-year 800% rally carries obvious risks. For that reason, I think there are better risk-adjusted opportunities out there at the moment.
For existing shareholders sitting on large gains, however, the decision does not have to be all or nothing.
If EOS has grown into a large part of a portfolio, trimming some shares could allow investors to lock in profits while still keeping exposure to the company's long-term growth potential.
Sometimes the best move with a big winner is simply to take some chips off the table while letting the rest run.
