** Shares of rare earth magnet company USA Rare Earth USAR.O rise 8% to $29.94 premarket

** Brokerage William Blair initiates coverage with "outperform" rating

** Brokerage says the U.S. government may announce sizable investment in company

** Adds that USAR has signed over a dozen partnership agreements for magnets and is in discussions with more than 70 customers

** "During a visit to the company’s neodymium magnet manufacturing facility in Stillwater, Oklahoma, we saw firsthand the quick production clip and the expansionary bulk volumes of critical metals/magnets," William Blair

** Says co will convert rare earths from its Round Top Deposit in West Texas into critical metals and magnets for industries such as defense, auto and electronic

** 4 of 4 brokerages rate the stock "buy"; their median PT is $21 - data compiled by LSEG

** Up to last close, stock up 141.5% YTD

(Reporting by Pranav Mathur in Bengaluru)

((Pranav.Mathur@thomsonreuters.com;))