Investors in GlaxoSmithKline, the pharmaceuticals giant, are demanding that the company take urgent steps to use its £2.3bn cash pile, or face the prospect of a shareholder rebellion.
Institutional investors are pressuring GSK to use the mountain of spare cash on its balance sheet to make acquisitions and to bolster its pipeline of new drugs.
Anne Marieke Ezendam of Threadneedle Investments, which owns GSK shares worth more than £150m, said: "I don't feel there is enough urgency at the company today. It needs to step up its efforts in buying and in licensing new drugs into the pipeline."
Another shareholder, who declined to be named, added: "Shareholders are simmering. GSK needs to take action now to use its balance sheet more effectively. Investors won't put up with the current situation."
Just a few months ago, the company's pipeline was the envy of the industry. But since Dr Tadataka Yamada, the research and development chief, left earlier this year, several projects have run aground.
"GSK keeps saying it has the biggest pipeline in the industry, but it's really not. The risky projects are too big a chunk," said Ms Ezendam. "My biggest worry was that when [Dr] Yamada left, half the products would drop out, and that's exactly what is happening."
GSK's highly anticipated cervical cancer vaccine Cervarix has been delayed by three months and Promacta, a treatment to help blood clotting, has been pushed back by a year. Meanwhile, Redona, a diabetes treatment, was put on hold after producing poor clinical data, and an anti-sepsis drug was scrapped.
GSK's share price has slumped 9 per cent in the past six months as investors flee to faster-growing companies in the sector.
The company's stable of prescription drugs is also coming under increasing pressure from cheap generics. Credit Suisse analyst Steven Plag estimated that nearly half of its sales in the US, the world's largest drugs market, were vulnerable to generics in the next few years.
Ms Ezendam suggested that Shire, the speciality drugs maker that has recently been rumoured to be in the sights of another industry giant, AstraZeneca, could be a logical option for GSK.
"They can buy companies with products already on the market, such as Shire, which has an attention deficit hyperactivity disorder franchise and some small orphan drugs that would fit quite nicely." Sources said a Shire purchase was unlikely.