Investec has retained its 'sell' rating and 1,000p target price for oil giant Tullow following a production miss on Friday morning.The broker said: "This morning's trading update delivered disappointing production figures for Tullow and underlined our view that it may not attain production of 100,000 bopd or more until as late as 2018 (disposal dependent). This will put greater pressure on the exploration portfolio to deliver exceptional results, we think."With global economic growth starting to gather momentum, Credit Suisse believes that increased risk appetite bodes well for asset managers and has upgraded its rating for London-listed firm Schroders from 'underperform' to 'neutral' as part of its sector review.The broker said that the decision was "driven by our more positive stance on net inflows into equities across retail and institutional clients, increased demand for multi-asset products and potential for revenue margin uplift following multi-year declines".British Airways and Iberia owner International Consolidated Airlines, otherwise known as IAG, was flying high on Friday morning after UBS upgraded its rating for the company from 'neutral' to 'buy' following the stock's underperformance last year."We think that IAG could be the laggard most likely to outperform in 2013 should it achieve the concessions the company wants from Iberia staff," the broker said in a research report.BC