The Dow average closed above 15,000 for the first time on Tuesday, but on Friday the Russell 2000 small-company index took new-record honors by closing the week up 2.2 percent. Investors are loving small stocks at the moment because they have a better chance of surging ahead than large, global companies do as the US economy continues to improve. The sharp increase is also a sign that investors are more willing to take on risk. Large Dow stocks like Exxon Mobil and Alcoa were held back by falling commodity prices Friday. Among the gainers were Priceline.com and chip maker Nvidia, which reported higher earnings.