The Thomson Reuters Post-Venture Capital Index (PVCI) dropped from 795.87 at the end of August to 694.73 at the end of September.
It was the first time that the PVCI dropped below 700 since August 2010.
The PVCI reached a high of 930.36 at the end of April, but it has been mostly declining since then as the public markets have soured.
The Index at the end of September was comprised of 570 companies, and of the stocks tracked by the PVCI, only 105 gained in value while 465 declined.
The PVCI tracks VC-backed stocks beginning at the point of going public. It is a market-valued index that measures the performance of public stocks of companies that have received financing from a U.S. venture capital firm or buyouts limited partnership prior to going public.
With no VC-backed IPOs in September, there were no additions to the PVCI.
Companies remain in the index for 10 years from the IPO date or until price data is no longer available, they are acquired or removed from a publicly traded exchange.
The index is calculated daily and does not take into account dividends. It began in January 1986 with an initialized index value of 100.