Peter Thiel’s Founders Fund is nearing the close of its fourth growth fund, Founders Fund Growth IV, with $6 billion in capital commitments, per sources close to the firm. As with most of the firm’s fundraises, demand from outside investors exceeds the fund’s capacity, according to those sources. Additionally, about $1.5 billion of the capital is coming from the Founders Fund’s partners, one of the sources told TechCrunch.

The fresh fundraise comes less than a year after Founders Fund closed its third growth fund, a $4.6 billion vehicle intended primarily for follow-on investments in its successful late-stage companies.