I see from search this has been requested a handful of times. It would be great if it were possible to just transfer securities--with the relevant cost basis information--from one brokerage to another. Recently I moved a managed fund from Schwab to Fidelity. It's taken over an hour to reconcile the accounts, much of which I had to accomplish by hand because MD doesn't allow securities to be transferred. After downloading transactions, Schwab, reported each sell as SellXfr with Price 100 and no balance, unhelpfully to my 15-years-closed Spanish bank account because it's first in the alphabetical list. Then Fidelity reported each as a BuyXfr from that closed checking account. To be clear, Schwab and Fidelity did not choose that account, that's a separate annoyance of MD.

Since I didn't catch the exact date of the transfer, by the time I caught it (a day later), Fidelity had sold all of the securities transferred from Schwab and purchased new securities, leaving me unable to see either Schwab's or Fidelity's reported cost basis for the old securities. Neither firm captures the cost basis in the xfer transactions because they recorded it as shares transferred and not sold/bought.

There's probably a way to find the historical cost basis for each of the 13 securities, but I couldn't quickly figure it out. To make both accounts at least display the correct current positions, I looked up the date-of-sale price for each security then entered it as a SellXfr at that price in Schwab. Then in Fidelity I converted its BuyXfr to a Buy and entered the same price as before. Rinse and repeat 12 times. I lost my cost basis, but now both accounts show the correct positions and cash balances. It was a lot of manual work that should be able to be managed by financial software in my opinion.