RARX filed an 8-K disclosure on 3/31 to announce the antitrust waiting period had expired at without any action by the FTC. Waiting periods can expire only if the antitrust review is not terminated early.
Among the risks throughout March that contributed to the large spread between market price and deal price was 1) the antitrust trust filing had been pulled and refiled twice already,and 2) the FTC had not yet granted approval, raising the odds there would be a second request which would delay closing for many months. Combine that with the upheaval in the credit markets and this partly debt-financed merger was not a sure thing to be completed this month.
Congrats if you took advantage of the large spread in prices by buying anytime in March. Just beware it was not nearly such a slam-dunk as you think.
"The waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended (the “HSR Act”), in connection with the previously announced proposed acquisition of Ra Pharmaceuticals, Inc. (the “Company”) by UCB S.A. (“UCB”) expired at 11:59 p.m., Eastern time, on March 30, 2020." https://www.sec.gov/Archives/edgar/data/1481512/000110465920040735/tm2014135d1_8k.htm