Im not sure how you have come to the conclusion that Vanguard is selling.
The number of shares they hold has gone from 13 million to 14.5 million and increase of 1.5 million shares.
If you look at the table under the holdings it says BUY, BUY, BUY in all 3 rows. The percentage has changed due to dilution from capital raisings but it pays to actually read the form accurately. I don't even hold CDU buy my brother-in-law works for vanguard so that caught my eye. Took all of 2 seconds to see they weren't selling.
CDU Price at posting:
$3.51 Sentiment: None Disclosure: Not Held