By Svea Herbst-Bayliss

BOSTON, (Reuters) – Jana Partners LLC was an activist investor who successfully pushed for major changes, including the sale of portfolio companies. Two sources claimed that investors were told by Jana Partners LLC that their JSI Benchmark portfolio had returned 30% last year after paying fees.

These gains were fueled in part by Vonage Holdings Corp’s sale and Laboratory Corp of America’s (NYSE:) Holdings’s share buy-backs and plan to pay a dividend.

As record-setting market gains helped investors, the portfolio’s returns last year outperformed the benchmark HFRI Activist Index’s 19% return.

The JSI Benchmark portfolio has returned on average 30% per year over the past three years after paying fees.

Jana Strategic Investment, which was structured more as a private equity fund than a traditional private investment fund, earned 26% in fees last year according to the sources. They aren’t allowed to talk about the returns of private funds. One source stated that the JSI fund has returned 18% per year since its inception in 2010.

Jana Partners filed also a preliminary prospectus to its second special-purpose acquisition company, Osprey Technology Acquisition Corp II.

The spokesperson declined to comment.

Three years have passed since Jana, which was established by Barry Rosenstein, announced that it would be closing its event-driven funds.

Fund manager, the firm has $1.6 billion under its activist strategy. It is well known for its efforts to push for Whole Foods reforms which led to Amazon’s sale (NASDAQ:). This fund manager is among the most highly regarded in its field, shunned by the media and working with other target companies.

Gordon Haskett, a research firm, named Jana their “activist-of-the year.”

Analyst Don Bilson stated that Jana was the only one who could catalyze more action and was more consistent at hooping than anyone else.

Jana’s return is largely due to the changes Jana made at target companies. It did not result from any gains in private investments or fast-growing technology companies.

Vonage Holdings shares rose 59% in May to November, when Ericsson announced that it was selling the company (BS:). Jana recommended a strategic review and LabCorp stock prices rose 54%. Jana also pushed for a sale of data center company Cyrus One which was taken private by buyout firms KKR & Co (NYSE:) and Global Infrastructure Partners.

Encompass Health (NYSE) is currently trying to disintegrate Zendesk (NYSE)’s plan to purchase Momentive Global. Mercury Systems (NASDAQ;) will now be looking at strategic alternatives.