Poison Pill

Poison pills are the most common takeover defense in public company land. They don't prevent acquisitions directly — but they make hostile acquisitions prohibitively expensive while allowing the board to negotiate from strength. The mechanics: if any shareholder accumulates more than a trigger threshold (typically 10-20%), the "pill" triggers, giving all other shareholders the right to purchase additional shares at a deep discount. This dilutes the would-be acquirer, making the acquisition much more expensive. Practically, poison pills force potential acquirers to negotiate with the board rather than buy directly from shareholders.

How it actually works: Classic shareholder rights plan mechanics: (1) Rights distribution — board distributes "rights" to all shareholders, initially worthless and not separately tradeable; (2) Trigger event — an acquirer accumulates stock above threshold (commonly 10-20%) or launches tender offer; (3) Flip-in provision — rights "flip-in" allowing non-acquirer shareholders to buy additional shares at 50% discount, diluting acquirer; (4) Flip-over provision — if the acquirer ultimately gains control, rights "flip-over" to allow non-acquirer shareholders to buy acquirer's stock at 50% discount, further diluting acquirer; (5) Redemption — board can redeem rights for nominal amount if they decide to accept a deal; (6) Expiration — rights typically expire after 10 years unless renewed.

The strategic effect: poison pills don't legally prevent acquisitions but make them economically unviable at unfavorable terms. The acquirer's only practical path is to negotiate with the board to redeem the pill — giving the board control over the process and timing. This shifts negotiating leverage dramatically toward the board.

Delaware's legal framework: poison pills have been upheld by Delaware courts (including the seminal Moran case) as valid defensive tactics, subject to "enhanced scrutiny" under the Unocal test (reasonable response to reasonable threat). Most public company boards have authority to deploy pills on short notice without shareholder approval.

Modern variations: (1) Low-threshold pills — 4-5% triggers, used to prevent 13D "activist" accumulation; (2) NOL poison pills — designed to preserve tax loss carry-forwards by preventing ownership changes; (3) Wolf pack provisions — address coordinated accumulations by multiple parties; (4) Sunset provisions — automatic expiration unless shareholders reapprove.

Shareholder activism has pushed back against poison pills. Institutional investors increasingly vote against pills without shareholder ratification, and "pill shelf" approaches (pills ready to deploy but not adopted) are becoming more common than standing pills.