Employees of the largest tech companies lost out on billions of dollars in potential returns because their employer-sponsored retirement plans were invested in fossil fuels, an environmental group reported.

The tech companies could have earned an additional $5.1 billion in returns if their 401(k) plans over the last 10 years had invested in the S&P 500, minus oil and gas equities, As You Sow and the University of Waterloo in Waterloo, Ontario, said in a report.

The report look at a 10-year period ending the beginning of this year and showed the oil and gas sectors underperforming the market despite recently good performance, As You Sow said.

The report included the retirement plans for more than two million employees of 12 major tech companies, including Amazon, Apple, Google, Meta, and Microsoft, Adobe, Broadcom, Intuit, Netflix, Oracle, Qualcomm, and SAP America.

“Despite these companies publicly announcing climate goals and often asserting climate-friendly branding, they continue to invest billions of dollars of employee savings into fossil fuels and other industries accelerating climate change,” the report said.

Amazon, Google and Apple either declined to comment on the report or did not return emails to their media offices.

“Investing in high-carbon industries is fueling the climate crisis and exposing investors to financial risk. These 12 companies have a responsibility to their employees, investors, and consumers, who want to see broad, consistent climate action,” Andrew Behar, CEO of As You Sow, said in a statement. “Addressing the systemic risk of investing in high-carbon companies is a proven win-win strategy for companies looking to reduce their financed emissions while protecting their employees from climate-related financial losses.”

The report focused on the largest tech companies because of their “outsized impact” on retirement accounts, Andrew Montes, As You Sow spokesperson, said in an email. “It is likely that these findings would hold true for plans offered by employers in other sectors,” he said.

The funds analyzed were equity funds and target date funds, using data from company filings with the U.S. Department of Labor. Nearly half of the assets analyzed were in target date funds from Vanguard and BlackRock, the world’s largest investors in fossil fuels, As You Sow said.

“We know fossil fuels have underperformed over the last decade, so the results shouldn’t be surprising,” Behar. “What is surprising is that nearly every retirement plan is invested in the extractive economy, which runs counter to the values of the people who earn the money while reducing their retirement savings.

“The solution is very simple: Big tech companies could easily ask asset management firms like Vanguard and BlackRock to offer sustainable target date and index fund options so their employees can avoid these under-performing and risky holdings,” he added.