Renowned Legg Mason manager Bill Miller bought a large stake in Transocean at the height of the BP turmoil, believing the owner of the stricken Gulf of Mexico rig got oversold during the crisis.
The FTSE 100 failed to respond to broker upgrades and healthy earnings reports in early trading, advancing only six points, or 0.1%, to 5,562.37 points.
The cost to BP of cleaning up the Gulf of Mexico oil spill has hit $8bn (£5bn).
M&G's Tom Dobell has boosted BP to the largest position in his £5.35bn Recovery fund, believing its recent decline represents a rare opportunity to invest in one of the UK's leading companies.