Subject: Re: Nope, Not Gonna Do It
What about the part about converting at a, premium?

If a broker uses “last price” as a shortcut to market value, as some are known to do, it can appear at times that 1500 B shares are trading at a market premium to a single A share.

my guess is this is what triggered the notification to call. The idea being one could convert the A share to 1500 B shares and unlock the higher (apparent) market value of the Bs.