Provisions in a loan agreement or indenture which give the lender the right to accelerate repayment of its loan (or renegotiate the loan agreement) or the bondholders the right to be redeemed at par if certain events occur before maturity of the debt. Events typically include a change of control, leveraged buyout, hostile takeover, large dividend payment, or company restructuring.

Generally poison puts act as a deterrent to takeover attempts by imposing significant repayment obligations on the acquiror. At times when the supply of credit is limited, however, poison puts can act as an impediment to M&A activity as companies are unable to renegotiate their bank deals or redeem their bonds.

In addition, in San Antonio Fire & Police Pension Fund v. Amylin Pharmaceuticals Inc. a poison put change of control provision in an indenture was challenged in the Delaware Court of Chancery on the basis of a change in the board of directors. The issue arose when two dissident shareholders each ran a different proxy slate of directors. In that case, shareholders argued that the poison put provision entrenched management because the company could not afford the put. The poison put issue subsequently became moot in that case after shareholders changed the number of directors nominated.