I prefer, in a case where you are moving an entire account to a new
broker to change the details on the account from the old broker to
the new broker. That way there is no ambiguities and things are
simpler. If you are using downloaded statements, stop that for the old
broker . Set up the new broker. If you download
some TransferOut or TransferIn transactions from the ACATS process,
just Void or Delete them. Note that your old broker may continue
to receive dividends for a month or two, and do an ACATS transfer
of funds periodically. During that period, you could keep the
transferred-in funds as deposits, or you could Void those, and
hand-enter the dividends.