One of the longest-running bull markets in history is celebrating its ninth birthday this month. So how long can it go? Weeks? Months? Years? And when it does correct — how low will it go? We asked Arthur Stein, a Washington-area financial planner who tracks the Thrift Savings Plan. He’s our guest on this episode of Your Turn, a radio show (Wednesday's at 10 a.m. EST) streaming on Federal News Radio or at 1500 AM in the D.C. area.