Curian Capital LLC, an asset management company based in the Denver Tech Center, plans to close down next year and stopped accepting new accounts effective today. It’s unclear what that means for the 300 employees who work out of the Curian offices near the intersection of interstates 25 and 225. Curian will continue to manage existing accounts into 2016 to allow financial professionals and clients sufficient time to plan for the transition of accounts, said Mark Mandich, interim president and…