City sources predict the FTSE 100 will open up around six points from Wednesday's close of 6,551.53, ahead of the release of UK and US gross domestic product later today. Britain's economic growth for the second quarter is expected to hold steady, according to forecasts ahead of figures released later today.GDP is tipped to come in at 0.7%, unchanged from the previous period. Earlier this month Chancellor George Osborne said the UK economy was "turning a corner" but warned that unemployment and the deficit were "still too high".Across the Atlantic, the progress of the US economy is also being closely watched amid debt ceiling talks and the potential of a Federal Reserve stimulus cut next month.As such, investors will be eyeing the release of US GDP figures which are forecast to rise to an annualised 2.6% in the second quarter from 2.5% in the prior three months.Last night, Wall Street benchmarks ended Wednesday's session slightly lower with the Dow Jones and S&P 500 finishing in the red for the fifth straight day as investors continued to view budget negotiations in Washington with caution.Markets are hoping that politicians can agree on a extension to the current debt-ceiling limit of $16.7tn ahead of the deadline on Tuesday October 1st to avoid a government shutdown when the new fiscal year begins.Back in the UK, today has seen Tullow Oil announce a new oil discovery in Northern Kenya. The group said results of drilling, wireline logs and samples of reservoir fluid indicate a potential net oil pay in the Auwerwer and Upper Lokone sandstone reservoirs of between 60 and 100 metres.A strong high season this summer and heartening early bookings for winter holidays has led tour operator TUI Travel to hike its profit guidance for the full year. The FTSE 100 company, which owns the Thomson and First Choice brands, said it was now confident of achieving at least 11% growth in underlying operating profits for the year to end-September.Design, engineering and project management consultancy Atkins said its overall performance in the six months to date remains in line with expectations, underpinned by strong growth in the UK. The outlook for the year remains unchanged and in line with expectations, it said, as it continues to weather mixed trading conditions.Pub and restaurant group Mitchells & Butlers has said it expects full-year results to be in line with expectations with sales growth coming in at 2.1 per cent. over the year to the end of September. However, like-for-like (LFL) sales were said to have tailed off in the fourth quarter due to tough comparatives with last year.FTSE 250 group RPS has acquired IChron, a UK-based consultancy providing geological and training services to the international oil and gas sector, to further its capability in its established and growing consultancy markets. RPS is acquiring the entire share capital of Ichron for a maximum total consideration of £12.5m, all payable in cash. The consideration paid to the vendors at completion was £6.6m, with further payments to be made if certain future conditions are met.