Interest paid by LPs admitted at subsequent closes to LPs admitted at first close, compensating early-closing LPs for the time their capital has been at work in the fund and bringing all LPs to the same economic starting point as of first close. Mechanics: subsequent-close LPs pay (a) their share of capital previously called, plus (b) interest on those amounts at an agreed rate (typically prime + 200 bps or fund's preferred return rate) from the date of original calls. A typical buyout fund's fundraising window (first close to final close) is 6-18 months, during which equalization interest can be material. Equalization is automatic in the LPA; without it, late-closing LPs would free-ride on early-closing LPs' capital.