People end up with several brokerage accounts for good reasons: an IRA at one firm and a taxable account at another, a legacy account nobody wants to move, a second platform with better tooling.

The trading is unaffected. The risk measurement is not, and the failure is quiet: concentration that would be obvious in one account becomes invisible when it is split across three.

Concentration hides in the gaps

Consider a book that looks entirely reasonable account by account.

Every row passes a 25% concentration rule. The combined position is 300 share-equivalents of one company and 22% of total net worth in the account structure — which is exactly the position the rule existed to prevent.

Four things worth consolidating

You do not need a unified view of everything. Four measures genuinely require it:

Exposure per underlying. Total share-equivalent delta plus actual shares, across all accounts. The single most important consolidated number.

Total capital committed. How much of your money is currently securing obligations, everywhere.

Sector and theme concentration. Three brokers makes it easy to end up with six positions that are all one bet on the same industry.

Realised P&L for the year. Needed for any honest performance figure, and needed separately per account for tax.

The double-count trap

The specific error to watch for when consolidating: the same position appearing twice because two exports overlap in time, or because a transferred position shows as a close in one account and an open in another.

Symptoms are a total capital figure larger than your actual net worth, or a share count that does not match what you can see in the accounts. Both are worth checking after every consolidation, because a double-counted position inflates exposure and can push you to close something unnecessarily.

The defence is a stable identity per position — broker, account, and the option's own identifiers — so the same contract cannot be counted twice under two labels.

Keep tax separate, deliberately

Consolidation is right for risk and wrong for tax. Each account has its own tax treatment, its own 1099-B, and its own wash sale considerations — and wash sales can reach across accounts, including from a taxable account into an IRA, which is a genuinely unpleasant edge case.

So the practical shape is two views: consolidated for exposure and performance, segregated for tax. Trying to make one view do both produces something wrong for both.

Doing it without much effort

Tag every position with its account. One column. It makes both views possible from one dataset.

Reconcile per account, review consolidated. Reconciliation is account-by-account because statements are. Risk review is across everything.

Normalise on import. Every broker exports a different CSV shape. Map them to one internal format once, rather than maintaining three parallel systems — see exporting trade history.

Check the total, not the parts. Whatever your concentration rule is, apply it to the consolidated figure. That is the only number the market responds to.

What can go wrong

Per-account concentration limits. The core failure, and it feels responsible while it happens.

Double-counting on import. Inflates exposure and prompts unnecessary closes.

Merging tax lots across accounts. They are legally separate; merging them produces figures that reconcile to nothing.

Only consolidating at year end. Concentration is a risk you want to see in March, not January.