The figures suggest a shift in profile of fraudsters from rogue executives to younger people funding extravagant lifestyles, said the researchers.
Overall, however, there was a 39% drop in fraud during the period to £317m.
The decline was helped in large part by a 72% drop in frauds committed by those aged 46 and over, to £88m.
According to the research, more than 400 people were conned into handing over sums ranging from £20,000 to £2m, yet their funds were used to purchase a Lamborghini and 5-bedroom house with a swimming pool among other things.
In one case a 30-year-old man convinced his victims to invest in vintage wine, which they believed would increase in value.
"Where once it was the jaded executive who relied on unquestioned seniority and authority to get away with dipping their hands in the till, it seems we are witnessing a changing of the guard," said Hitesh Patel, UK forensic partner at KPMG.
"Today's fraudster is younger and just at ease with using technology and data as selling promises," he said.
Another case involved a crooked financial adviser who bought a fleet of supercars, invested in a racehorse and sponsored two Premier League football clubs with the proceeds of his con artistry.
His scam involved the creation of a bogus investment fund for which he persuaded investors to hand over large cash sums, which he simply spent.
One victim was so convinced that he parted with £3.7m, none of which has been recovered.
Frauds committed by those aged 26-35 were up 285% in the first half of the year - to just over £62m - according to research by accountants KPMG.