UBS has reiterated its buy rating on oil titan BP following its $4bn settlement with Anadarko, which the broker sees as an "important step towards resolution".On Monday, BP and US counterpart Anadarko have reached a settlement over the Deepwater Horizon rig explosion at the Macondo asset in the Gulf of Mexico. Anadarko will pay BP $4bn in a single cash payment, which will go into the $20bn trust fund BP set up to meet individual, business and government claims relating to the tragic incident, as well as the cost of the natural resource damages. "The level of settlement and the costs incurred to date suggest to us that the provisioning for environmental costs and economic charges may be too high and BP may be successful in gathering more contributions than we assume - however this may take time to establish and other penalties may also become apparent," the Swiss broker said.UBS says that the settlement with the US government and the closing of the Department of Justice investigation are now the "critical stepping stones". This, the broker says, should bring an end to the issue and free up the company to get back to work in the Gulf of Mexico.The target price from 450p to 480p to reflect the de-risked valuation.BP was among the best performers on Tuesday morning, rising 0.95% to 429.6p by 10:00, bucking the trend as the Footsie sank 1.02%.BC