A demand, usually in writing, by a company or investment fund (such as a private equity fund) for payment of any part of the balance committed to it by an investor under an existing capital commitment.

Capital calls are most common in the context of investment funds, where an investor (or limited partner) becomes a participant in a fund by subscribing for a capital commitment. In most cases, the commitment is not funded at subscription or even all at once, but in separate capital contribution installments, which the sponsor designates by making capital calls on an as-needed basis to make investments and to pay fees and expenses over the life of the fund. The sponsor's ability to call for capital contributions from its investors is limited at any time to the extent of each investor's unfunded commitments (the investor's total commitment less contributions already made). For more on capital calls and private equity fund formation, see Practice Note, Private Equity Fund Formation and Timeline of a Private Equity Fund.