Neil Woodford and Lord Jacob Rothschild, two of the most successful investors in the UK, have in their different ways, warned against irrational stock market exuberance.

In the first interim report covering the quarter to June for his new investment trust Woodford Patient Capital, which has a strong allocation to biotech companies, Neil Woodford said there was huge enthusiasm for cures for a range of ailments. But he added: "This has led to several US biotech stocks trading on bubble-like valuations. We have focused our attention on purpose stocks where future potential is, in our view, significantly undervalued by the market."