Photo taken on Oct. 10, 2016 shows the portraits of the two winners of the 2016 Nobel Prize in Economics on a screen at a press conference held by the Royal Swedish Academy of Sciences in Stockholm, Sweden. The 2016 Nobel Prize in Economics, or officially the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel, has been awarded jointly to Oliver Hart and Bengt Holmstrom "for their contributions to contract theory". (Xinhua/Shi Tiansheng)