Zymergen Inc. received a nice reception on Wall Street in its public debut, as the stock opened 30% above its initial public offering price. The “biofacturing” company said overnight that its upsized IPO priced at $31 a share, at the top of the expected range of between $28 and $31 a share. The stock’s first trade was at $40.30 at 12:43 p.m. Eastern for 876,313 share. At that price, the company was valued at about $3.85 billion. The stock has pared some gains since the open, and was last trading up 17.0% at $36.27. The company went public on a day that the Renaissance IPO ETF rallied 2.4% while the S&P 500 ticked up 0.1%.

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