Oklahoma should end a capital gains tax exemption that benefits high-income residents and cost state coffers $465 million over five years, a state board was told last week.

For more than a decade, the state has allowed profits from the sale of Oklahoma-based property and stocks to be fully deductible in hopes of spurring investment. Pennsylvania-based PFM Group Consulting says that hasn't worked.

“The incentive overall cannot, with the data available, be credibly shown to have significant economic impact or a positive return on investment for the state,” the company wrote to the Incentive Evaluation Commission.

From 2010 to 2014, the tax breaks created an estimated $9 million in additional tax revenue while costing state coffers $474 million, a net loss of $465 million for the state. PFM found that 86 percent of the tax breaks went to residents making at least $200,000 annually.