Electro Optic Systems Holdings Ltd (ASX: EOS) shares are having a day to forget on Tuesday.
After trading largely flat for most of the session, the ASX defence stock is now down 25% to $8.00 in late trade.

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Why are EOS shares crashing today?
The company's shares are crashing following the release of an announcement detailing significant insider selling after the exercise of options.
According to the release, EOS' CEO and managing director, Dr Andreas Schwer, the CFO/COO Clive Cuthell, and other members of the management team have exercised a total of 3,429,299 options to acquire 3,299,599 EOS shares.
These options were granted under the company's long-term incentive plan after performance and service hurdles were met during the 2024 and 2025 financial years.
Management was able to exercise the majority of these options for just 50 cents each.
Planned share sales
However, rather than hold onto these shares, senior executives intend to sell a large portion of them.
The release notes that its CEO, Dr Schwer, has been approved to dispose of up to 2,500,000 shares in the near term, with the final number to be determined within that limit.
Based on yesterday's close price of $10.72, these shares had a market value of $26.8 million.
The company notes that this planned disposal is intended to allow him to fund personal expenses, including the construction of a family home and a divorce settlement.
In addition, the CFO/COO and other members of the management team have indicated that they also intend to dispose of some or all of their shareholdings in the near term.
Minimum holdings still met
Despite the planned disposals, the company expects that both Dr Schwer and Mr Cuthell will retain shareholdings well above the minimum levels required under its recently announced shareholding policy.
This is a minimum of four times the CEO's fixed annual remuneration and three times the CFO/COO's fixed annual remuneration.
Nevertheless, investors appear to be reacting negatively to the scale of the potential insider selling.
After all, insider selling is often seen as a bearish indicator, as few insiders would be happy to part with their shares if they felt that they were about to increase in value.