You can buy back up to 1/4 of the recent average daily trading volume. I don't know what constitutes "recent", but it's possible that they're OK, after yesterday's 31M bumped up the volume.
Ironically, all that "below the bid selling to selves" price manipulation, if that's what a lot of the recent big blocks really were, helped boost average volume a lot, which is helping the buyback happen faster now.
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