 Shares of NanoString Technologies Inc. ntsg plunged 32.8 toward a two-year low in morning trading Wednesday, enough to make them the biggest losers trading on major U.S. exchanges, after the provider of life science discovery tools warned about a revenue miss, citing execution missteps. The company said late Tuesday that it now expects first-quarter product and service revenue of 31 million, below the previously provided guidance range of 34 million to 38 million. 