Goldman Sachs is perplexed by the share price recovery from part-nationalised bank Royal Bank of Scotland from 35p in mid-July to more than 50p. The US investment bank expects RBS to remain loss-making in the short term, while the threat of another cash call continues to hang over the bank's shares. Goldman Sachs suggests that as an alternative to a rights issue RBS could sell off some or part of its US operations in order to reduce debt.US investment houses Goldman Sachs and Merrill Lynch dealt oilfield support services group Petrofac a double-blow on Friday with some bearish comment. Merrill Lynch has downgraded Petrofac to 'underperform' from 'neutral', with a price target of 930p. The US broker believes that the recent improvement in contracting activity has been at the cost of reduced margins. Goldman Sachs goes a little easier on the stock, downgrading it to 'neutral' from 'buy' after the share price's recent good run.Oil groups are going well despite the steady decline in the price of crude over the past few days. It dropped below $66 per barrel last night but has recovered a tad this morning. Tullow Oil and Cairn Energy are the best performers in the sector, though the big guns BP and BG are also firmer. Tullow gets a lift from Goldman Sachs raising its target price to 1396p from 1160p.FTSE 100 - RisersTullow Oil (TLW) 1,172.00p +2.90%Pearson (PSON) 778.00p +2.50%Compass Group (CPG) 359.70p +2.39%Centrica (CNA) 260.10p +2.32%British Sky Broadcasting Group (BSY) 569.50p +1.70%BG Group (BG.) 1,082.00p +1.41%BHP Billiton (BLT) 1,691.50p +1.35%Liberty International (LII) 499.20p +1.34%Shire Plc (SHP) 1,072.00p +1.23%Rexam (REX) 259.30p +1.21%FTSE 100 - FallersTUI Travel (TT.) 259.80p -3.49%Fresnillo (FRES) 745.50p -3.18%Petrofac Ltd (PFC) 944.50p -3.13%Eurasian Natural Resources (ENRC) 850.00p -3.08%Invensys (ISYS) 290.30p -3.07%Lloyds Banking Group (LLOY) 103.85p -3.03%Old Mutual (OML) 97.25p -2.94%Inmarsat (ISAT) 542.50p -2.86%Thomas Cook Group (TCG) 240.00p -2.36%Vedanta Resources (VED) 1,896.00p -2.32%