March 11 (Reuters) - Shares of SoftBank-backed Coupang were set to open more than 40% above the offer price in their market debut on Thursday, after the South Korean e-commerce giant raised $4.55 billion in the biggest U.S. initial public offering this year. At 10:13 a.m. ET, the stock was set to open at a range between $45 and $50, compared to the raised offer price of $35 per share. (Reporting by Niket Nishant in Bengaluru; Editing by Sriraj Kalluvila)