(ShareCast News) - Sir Martin Sorrell's WPP posted a 44.5% boost in first half pre-tax profit to £709.7m from £491.1m, off reported revenue growth of 6.8% to £5.839bn from £5.469bn.The advertising giant said a stronger third quarter was likely, as budgeted and forecast.WPP upped its dividend per share by 36.9% to 15.91p , which it said was significantly higher than the traditionally lower first half pay out.The advertising firm said it was engaged in a "tsunami" of media investment reviews, mostly in the US, totalling $20bn, and was awaiting further results."The group continues to benefit from consolidation trends in the industry, winning assignments from existing and new clients, including several very large industry-leading advertising, media and digital assignments, the full benefit of which will be seen reflected in group revenue later in 2015 and into 2016."WPP said while clients were more confident than in September 2008, and had stronger balance sheets, they were unwilling to take further risks, and so focused on costs rather than revenue growth."Procurement and finance take the lead over marketing and investment and suppliers are encouraged to play the additional roles of banks and/or insurance companies," WPP said.WPP said it forecast a stronger second half, partly due to easier comparatives in 2014.Full year like for like net sales growth was likely to be more than 3%, after WPP reported like for like net sales growth of 3.7% in July.