It would seem correct that a buyback plan authorized by the BOD having no knowledge of material positive information at time of authorization would allow the company to buyback it's own stock without concern of the SEC after that date. Others have posted how the regulations about buybacks deal with the volume and price allowed for purchase during the day and no buybacks in the first and last half hour of trading.
If you count up the major block trades over the last 2 weeks in the AH staring with the 232K block on the 16th, it's close to 900K shares, of course buying could have been occuring during the day as well. FWIW, today there a 2 separate block trades of 18,800 and another for 10,000 along with 2 trades of 7500 each and another for 5800.
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