By Colin Kellaher 



  Avidity Biosciences Inc. said an upsized initial public offering of 14.4 million shares was priced at $18 each, the high end of the expected range. 


  The La Jolla, Calif., preclinical-stage biopharmaceutical company Thursday had said it expected to offer 12 million shares at $17 to $18 apiece in the IPO, up from previous plans to sell 10 million shares at $14 to $16 each. 


  Avidity, which is backed by Eli Lilly & Co., said it expects gross proceeds of roughly $259.2 million from the offering. 


  Shares of Avidity, which has granted the underwriters a 30-day option to buy up to an additional 2.16 million shares, are expected to begin trading Friday under the symbol RNA. 


  Write to Colin Kellaher at colin.kellaher@wsj.com