Berenberg has maintained its 'buy' rating on global banking group HSBC, saying that its transformation has gone unrewarded by the market."We believe HSBC has transformed itself into a bank that is comparable to the one that outperformed its peers and the market between 1992 and 2003. This appears to have been ignored by the market, with HSBC trading at a 15-year relative low to the UK market and at a 10% valuation discount to the European banks, a 13-year low," the broker said.UBS sees 'significant headroom for growth' at British Sky Broadcasting (BSkyB) and identified a number of new opportunities for the broadband and pay-TV group. The bank reiterated its 'buy' recommendation and 1,100p target price for the stock.UBS believes that growth will be driven mainly by new products such as NowTV and Sky Go Extra. Operational gearing for a number of these products is "relatively high", the bank said. UBS also sees a "meaningful" opportunity in the company's new advertising product, Adsmart, and possibilities within mobile.The outlook at industrial engineering firm Weir Group is 'fairly subdued', according to Investec, which has lowered its stance on stock from 'add' to 'sell'.The broker admitted that downside to forecasts is now limited, but said that at current levels the stock is pricing in a strong recovery in oil and gas markets in 2015. "Yet for us, this is far from clear," it said.Digital sports media firm Perform Group was trading with heavy losses on Friday after Credit Suisse downgraded the stock from 'outperform' to 'neutral'.The bank has raised its target price for the shares from 246p to 290p after the company's better-than-expected 2013 results reported last week. However, after a 50% rally in the share price since Perform's December pre-close trading update, it believes that the stock is now "fairly valued", trading at 27.3 times estimated earnings for 2014.Canaccord Genuity has cut its rating for oil explorer Gulf Keystone Petroleum (GKP) from 'hold' to 'sell' after an audit of its Shaikan project in Iraq found lower-than-expected reserves. The target price has been nearly halved from 195p to just 100p.The broker said that while Shaikan "remains the jewel" of GKP's portfolio, it looks "smaller and more complex than before and its other assets of Sheikh Adi, Akri Bijeel and Ber Bahr "provide only slender support to the resource figure".BC