Why Is Avrobio (AVRO) Stock Moving Today?

Group 1 - Avrobio is preparing for a merger with Tectonic Therapeutic, which is set to take place today after investor approval [1] - A one-for-12 reverse stock split will occur after market close today, with shares trading on a split-adjusted basis starting tomorrow [2] - The stock ticker will change from AVRO to TECX following the merger, with Tectonic Therapeutic becoming a wholly-owned subsidiary of Avrobio [2] Group 2 - AVRO stock experienced slight increases in the morning, but there were reports of a significant drop in pre-market trading, possibly due to merger and reverse stock split plans [2]