** Brokerage Jefferies downgrades EV maker Rivian RIVN.O to "hold" from "buy", PT unchanged at $16

** Jefferies says Rivian's Q1 results were better than expected, partly due to a new accounting treatment for previously received funds from a joint venture with VW VOWG.DE

** Brokerage sees upside to RIVN's brand and software capabilities, but is waiting for updates on the company's R2 program and potential partnerships with other companies

** Jefferies revises FY revenue estimates for RIVN due to rising capital expenditure, weak demand outlook for this year and lower production of units

** As of last close, RIVN stock up 11.8% YTD

(Reporting by Padmanabhan Ananthan)

((Padmanabhan.Ananthan@thomsonreuters.com))