Your broker doesn’t hold your records, the brokerage company (Vanguard, Fidelity, etc) does and all transactions are backed up as soon as they are made.
You can usually also enter new transactions even in the middle of the night except when the computer is down for maintenance. (That is easily seen on January 1 each year as they do their year end processing and set up for the next year.)
The statements your advisor gave you or mailed to you were for a particular point in time in the past.