Carta, a technology firm that helps other companies manage their equity shares held by various owners, is using data it has collected to create “The most thorough measurement of U.S. private companies’ performance.” The company, formerly called eShares, specializes in capitalization table management and valuation software and, unless a client specifically requests otherwise, anonymously aggregates data to create the Carta 100 Index.

Unlike with public companies, tracking marketwide performance of private firms is challenging, and analysts and industry experts often rely on fragmented information or anecdotal evidence to track private market trends.

“We believe the Carta 100 Index provides the most thorough measurement of U.S. private companies’ performance, and we hope this index provides new insights on the funding environment for private companies,” Carta said in a statement about the index.

Not surprisingly, the value of the index’s 100 companies has surged alongside public ones since it began tracking firms on June 30, 2017.

A year ago, the index was valued at 102.9 and it has since.