Spot gold smashed through $4,000 an ounce for the first time, as concerns over the US economy and a government shutdown added fresh momentum to a scorching rally. It’s a milestone for bullion, which traded below $2,000 just two years ago, with returns that now outstrip those for equities this century. Bloomberg's Valerie Tytel reports. -------- More on Bloomberg Television and Markets Like this video? Subscribe and turn on notifications so you don't miss any videos from Bloomberg Markets &