Cambridge Associates weights its VC index by pooled cash flows

The record

Cambridge Associates publishes a quarterly US Venture Capital Index and Selected Benchmark Statistics book. As retrieved on 16 September 2026, the edition posted is dated as of 31 March 2026 and states the index is built from 2,836 US venture capital funds, including fully liquidated partnerships, formed between 1981 and 2026. The book's own description of its measurement method says Cambridge Associates "uses the pooled horizon internal rate of return calculation to calculate the official quarterly, annual, and multi-year index figures." A horizon IRR is a money-weighted return measured between two dated points, treating a beginning net asset value as an inflow, interim cash flows at the mid-period date, and an ending net asset value as an outflow, reported net of fees, expenses, and carried interest to limited partners.

What the sources establish

The distinction matters because a pooled calculation is not the same statistical object as an average of individual fund returns. In a pooled horizon return, the cash flows of every qualifying fund are combined into a single set before the internal rate of return is solved for, so larger funds' cash flows carry more weight than smaller funds' cash flows do; that differs from a simple or asset-weighted average of each fund's own IRR. The CA benchmarks FAQ adds a second layer: the data comes from "the quarterly unaudited and annual audited financial statements that private investment fund managers produce" for their own limited partners, not from Freedom of Information Act requests, regulatory filings, or manager surveys, which is how CA distinguishes its index from a survey-based estimate. The FAQ also states the benchmarks run on "a one-quarter lag."

Scope and revision

The index covers only funds Cambridge Associates classifies as institutional quality: closed-end, commingled vehicles that invest third-party capital, screened away from corporate balance-sheet vehicles and single-LP funds, per the CA benchmarks page. The database is not static: CA's own text states the pool of contributing funds changes as managers stop reporting or backfilled histories are added, so a historical quarter's return can move between editions. That is a stated scope condition, not an error correction, but it means a March 2026 vintage and a later vintage covering the same trailing period are not guaranteed to match. The book is a living document, and every figure carries the date of its edition.

The decision in front of you

For an LP or fund manager quoting a CA index return in a memo, name the edition date alongside the number, since the same trailing-period return can differ across editions as the fund sample changes; this is editorial, not an instruction the sources give. It is also worth confirming a comparison return is genuinely a pooled horizon IRR before treating it as comparable to CA's figure.

• Which edition date is attached to the CA return being cited?
• Is the comparison return also a pooled horizon IRR, or a different weighting method?
• Does the fund sample match the strategy and vintage range being discussed?

A headline index return compresses a lot of methodology into one number, and naming the calculation method keeps it honest.