AthenaHealth Inc. shares surged 24% in Monday morning trade after activist investor Elliott Management said it plans to acquire the company for $160 per share in cash, in a deal valued at about $7 billion. AthenaHealth shares closed at $126.08 per share on Friday. Elliott already has an about 9% stake in AthenaHealth, and previously approached the company about taking it private in November, it said in a letter to AthenaHealth’s board of directors, but AthenaHealth “refused to engage.” “Unfortunately, we are faced now with the stark reality that athenahealth as a public-company investment, despite all of its promise, has not worked for many years, is not working today and will not work in the future,” Elliott Management said in the letter. “Given athenahealth’s potential, this reality is deeply frustrating, but the fact remains that athenahealth as a public company has not made the changes necessary to enable it to grow as it should and to create the kind of value its shareholders deserve.” Elliott claimed in the letter than AthenaHealth has among its problems executive turnover, a lack of operating effectiveness, issues with product and strategy execution and poor forecasting and guidance. News of the bid was first reported by CNBC. Company shares have dropped 6% over the last three months, compared with a 0.7% drop in the S&P 500 and a 2.5% drop in the Dow Jones Industrial Average .