May 14 (Reuters) - Activist investor Jana Partners built

a new stake in U.S. diagnostics company QuidelOrtho ( QDEL )

during the first quarter, sources familiar with the hedge fund's

position told Reuters.

It is unclear whether the hedge fund will seek changes at

the company, which makes the popular QuickVue COVID-19 test for

home use, and it could not be determined how large Jana's stake

is.

A representative for Jana declined to comment and a

representative for QuidelOrtho ( QDEL ) could not be immediately reached

for comment.

By building the position however, the hedge fund is signaling

its interest in the company and that it has already committed

significant resources to what could become an activist campaign.

The stake could be revealed publicly when Jana makes its 13F

filing, which requires fund managers to detail their ownership

in publicly traded U.S. companies for a given three-month

period.

QuidelOrtho ( QDEL ) currently has a market valuation of roughly $2.8

billion and its stock price has tumbled more than 50% in the

last 52 weeks. Since January the stock price has dropped 44%.

The San Diego-headquartered company fired Chief Executive

Officer Douglas Bryant, who had led the company for roughly 15

years, in February after fourth quarter earnings and revenue

fell, in part because COVID testing had dropped off. This month

it appointed Brian Blaser as president and CEO.

Jana has a 23-year track record of investing in companies,

including Frontier Communications, which recently

launched a formal strategic review following pressure and

Freshpet ( FRPT ), which has generated a return of approximately

250% in the two years since Jana began engaging with the

company.

Before that, Jana pushed for changes at companies such as

Whole Foods Market, which sold itself to Amazon.com Inc

(AMZN.O).