Tender Offer Arbitrage and the Odd-Lot Trick

In a tender offer — where an acquirer offers to buy shares directly from shareholders at a fixed price, rather than through a shareholder vote — the offer can be oversubscribed, meaning more shares are tendered than the acquirer agreed to buy. When that happens, most tendering shareholders get only a prorated fraction of their shares accepted at the offer price, with the rest handed back. But odd-lot holders — those tendering fewer than 100 shares, the standard "round lot" size — are typically guaranteed full acceptance of their tender, a protection built into most tender offer terms specifically to spare small retail holders the administrative hassle of partial fills.

This creates a small, well-known arbitrage niche: if a tender offer price is comfortably above the current market price and looks likely to be oversubscribed and heavily prorated, an investor can buy fewer than 100 shares of the target, tender the full odd lot, and be guaranteed 100% acceptance at the tender price — capturing the full arbitrage spread with certainty, while ordinary round-lot holders get only a prorated (and therefore diluted) share of that same spread.

The strategy's returns are capped by its own structure: since an odd lot is by definition fewer than 100 shares, the absolute dollar profit per position is small, and the trick only works when there's genuine reason to expect proration (an offer for far fewer shares than are outstanding, trading meaningfully above where the stock would sit if the deal failed).