Would you invest long term in a retirement instrument where the rate of return goes down every year for decades? You probably already do. That’s the case with the Thrift Savings Plan’s G fund, favored by many federal investors as a bulwark against volatility. Over the past 30 years, it’s delivered steadily declining rates of return. Federal News Network’s David Thornton looked into the G Fund and joined Federal Drive with Tom Temin for more on what he found.