daniel mitchell of the cato institute and ross isenbray. >>> stocks end the day mixed and little change. no major economic data to speak of today. no big earnings reports out. tensions between russia and ukraine seem to ease a bit on a ramp up of diplomatic efforts. the dow lost 11 points, the nasdaq gained 14, snapping a losing streak. the s&p 500 closed a fraction higher. >>> copper prices ended the day slightly higher, up one penny a pound that. brought an end to a sharp three-day slide and a 12% tumble in prices this year. that's reverberated through the commodity trading floors everywhere. bertha coombs tells us why the falling price for copper matters to all investors. >> reporter: the copper trade is all about china. the country's massive buildout over the last decade has driven global prices. but china's recent slow down has triggered investor concerns about the outlook for copper demand. concerns economist zach carable calls overblown. >> it's not as if the overall activity within china has gone from massive to minimal. it's that the pace has changed. >> reporter: but it's more