The gap in your
performance history.

Custodians commonly retain three years. Most established firms have been operating far longer. The difference has to live somewhere.

The gap most firms do not know they have

Custodians commonly retain three years of detailed transaction history. Many firms have been operating for ten, fifteen, twenty. If your performance record reaches back further than your custodian's retention — and for most established firms it does — then some part of your track record exists only in a system you may not control, in a format you may not own, reconciled by a process you may not be able to reproduce.

Nobody discovers this on a good day. It surfaces during a platform change, an examination, or due diligence on a sale — the three moments when it is most expensive.

Why it happens

Not negligence. Structure. Performance history is derived, not stored: a return is calculated from positions, prices, flows and corporate actions. Change any input and the output changes. So a track record is only as durable as the reconciliation that produced it, and reconciliation lives in whichever system was doing it at the time.

Move platforms twice in a decade and your history has been reconstructed twice by two different processes with two different assumptions about how to treat a flow.

What we found in the worst case

The longest transition we have run was a billion-dollar book coming off a legacy platform. It took months, and the software was not the reason.

Their history had holes. The custodian held three years; more than ten were needed. Reconstructing the gap meant going back through transactions that had not been reconciled in a decade, resolving corporate actions nobody had documented, and rebuilding composites that had been carried forward on trust. It ran to hundreds of hours of our people's time.

The firm did not know the gap existed. They had a number on a report and had reasonably assumed there was something underneath it.

How to find out before someone else does

Four checks, none of which require a vendor.

1. Ask your custodian how far back they retain detailed transactions. Get the answer in writing.
2. Compare that to the start date on your longest-running composite or client report. The difference is your exposure window.
3. Pick one account inside the window and rebuild a single year by hand. If it reconciles, your records are better than most. If it does not, you have found the problem cheaply.
4. Ask who has verified anything before the window. If the answer is a previous vendor, ask whether you have their working files or only their outputs.

What to insist on when you move

• Your history reconstructed and reconciled, not carried across on trust.
• The gaps identified and named before you commit, not discovered afterwards.
• A parallel run that compares old to new line for line, with the right to stop if they disagree.
• Your data leaving in standard formats at any point, including the working files rather than just the reports.

Any partner who has done this often will volunteer where the difficulty is. One who says the migration is straightforward has either not looked at your history or has not done many.