BP and contractor Halliburton were aware the cement used in the well in the Gulf of Mexico was unstable, an official US commission investigating the fatal explosion said. The US company conducted four tests between February and April on the cement slurry that were relevant to the Macondo well, with three concluding that the mix was unstable, the Telegraph reports.Royal Dutch Shell warned that the impact of a drilling ban in the Gulf of Mexico could last for another two years as it unveiled an 18% surge in profits to $3.5bn. Simon Henry, chief financial officer, said Shell was hit by a $115m (£72m) charge during the three months to September 30 because of the ban, which forced the group to leave rigs idle and delay plans for a string of exploration projects. He said that further losses were likely in the fourth quarter and next year, the Times reports.Next week's rise in the cost of air travel will make family holidays "unaffordable for many", Sir Richard Branson's airline Virgin Atlantic warned yesterday. Air passenger duty (APD) will rise by up to 55%, with those taking trips to Asia and Australia particularly badly hit. Duty for economy class flights to the Caribbean will double to £75. Economy flights to America will rise by up to a third to £60 per person, while taxes on flights to Asia and Australia will increase by 55 per cent to £85, the Times reports.High-earning men whose partners or wives fail to tell them they are claiming child benefit will be liable for heavy fines, according to Treasury enforcement plans to recoup the benefit from higher-rate households. Under a more complex and potentially intrusive tax regime from 2013, higher earners will be legally required to declare if their household claims child benefit so the payment can be clawed back, the FT reports.Santander, Spain's largest bank, is pressing ahead with plans to list part of its UK business on the London Stock Exchange, paving the way for the biggest British initial public offering since the financial crisis. The group is preparing to float up to 20 per cent of Santander UK, the business formed by the tie-up of its UK brands - Abbey, Alliance & Leicester and Bradford & Bingley - in the first half of 2011, the FT reports.Investors face large potential losses on eurozone debt under German plans likely to win backing from EU leaders on Friday - risking a boycott of Greek, Irish, and Portuguese bonds. Germany has agreed to give the EU's €440bn (£383bn) bail-out fund permanent status rather than letting it expire in 2013 as planned, but only as part of a "Crisis Resolution Mechanism" that forces bondholders to share losses from any future bail-outs, the Telegraph reports. The Tokyo Stock Exchange is investigating allegations of insider trading in firms that recently announced capital raising plans, dealing a possible blow to investor confidence. "We have received complaints from investors about possible insider trading. We are paying special attention to the particular cases," a TSE spokesman said earlier today, the Times reports.Microsoft confounded the critics yesterday when it reported that profits grew by more than 50% in the first quarter. The vast majority of profits still come from Windows and Office, which are under heavy attack from a new wave of mobile personal computing devices and online applications that do not require the software. Despite this threat its latest quarterly results showed a 25% increase in revenue to $16.2bn (£10.1bn), the Times reports.The chief executive of Blacks Leisure has launched a vigorous defence of the insolvency procedure that saved the outdoor retail specialist from collapse last year, as a smaller 27-store rival retailer Go Outdoors emerged as a bidder for the company. The comments by Neil Gillis on company voluntary arrangements (CVA) - which last year enabled the operator of the Blacks and Millets brands to ditch 88 unprofitable stores - came as Blacks Leisure reduced its first-half losses, reports the Independent.Traders at HSBC and JPMorgan Chase placed "spoof" orders so as to manipulate prices in the silver market, according to lawsuits filed against the pair. The claims from two independent silver traders follow reports that a "whistleblower" in the London office of JPMorgan has been helping regulators in the US with a two-year investigation into whether the silver market has been rigged, the Independent reports.