UK stocks are expected to rise for a third straight day on Friday, though investors will likely keep a close on developments in Ukraine. City sources predict the FTSE 100 will open around 15 points higher than Thursday's close of 6,685.26.The second estimate of UK gross domestic product (GDP) for the second quarter will be released on Friday on an otherwise quiet day for European economic data.GDP is expected to have expanded 3.1% in the second quarter, in line with the preliminary estimate.In the States, the producer price index, Empire State manufacturing, industrial production and University of Michigan consumer confidence will keep US investors busy later on.Stocks to watchBHP Billiton said that it is considering a demerger of certain assets in an effort to make the company "simpler and more productive". The company, which is the largest mining company in the world by revenues, is currently undergoing its "next phase of simplification".Construction group Balfour Beatty has again rejected Carillion's takeover proposal, branding it "opportunistic" and accusing Carillion of wanting to reduce Balfour's UK construction revenues by up to two thirds.FTSE 250 investment trust RIT Capital Partners said that net asset value (NAV) per share hit an all-time high of 1,401p by the end of the first half. However, the company gave a cautious outlook on the current state of stock markets, saying that it is "sceptical as to wether the current degree of investor complacency can be maintained".BC