Sometimes it is safer to jump off a cliff than to stand and fight. That is the issue facing managers of large US pharmaceuticals companies trading at their lowest valuations in years as they face varying degrees of “patent cliffs”, with blockbusters losing protection at a faster rate than they can be replaced.

The five big pharmaceuticals companies most affected by such concerns are Pfizer, Merck, Wyeth, Eli Lilly and Bristol-Myers Squibb. With average dividend yields of 5.7 per cent and forward earnings multiples of just 8.1 times, they trade more like conservative, cash-cow utilities than companies at the cutting-edge of science. Average share price performance is almost exactly in line with the broader market, down 35 per cent over the past year.