Trade Allocation Policies and Cross Trades

A manager running many client accounts against similar strategies rarely trades for just one client at a time — it's more efficient to bundle a buy order for the same stock across dozens of accounts into a single large order sent to the market, then split the fill back out afterward. That split is where a serious conflict of interest lives: if the order only partially fills, or fills at several different prices through the day, which clients get the good price and which get the bad one, and which clients get filled at all? A trade allocation policy is the pre-agreed, documented rule that answers this before any order is even placed, so the manager isn't making that call trade by trade with the benefit of hindsight.

How allocation is meant to work

The standard-practice fix is to decide the allocation method before the order goes out — commonly pro-rata by order size, or average-price allocation where every account that participated gets the same blended average fill price regardless of which specific fills it got. Average-price allocation is popular precisely because it removes the temptation to favor one account: a fund's flagship account and a small side account both get the identical $50.12 average price on a partial fill, rather than the flagship account somehow getting the best individual print. Consistent, documented allocation is largely what regulators check for — a pattern where the same account always seems to get the best fills is treated as a red flag even without proof of intent.

Cross trades — where the manager sells a position from one client account directly to another client account inside the same firm, without going to the open market — get extra scrutiny because there's no independent market price forcing fairness onto the trade; the manager itself is choosing the price on both sides at once. Regulators typically require cross trades to be priced at an independently verifiable market reference (like the day's closing price) and often require client consent or an independent fiduciary sign-off before a cross trade is permitted at all.

What this means in practice

A quant fund running many separately managed accounts against one signal needs an allocation policy built into the order management system itself, not just a written procedure — average-price allocation logic has to be coded in so it applies automatically rather than depending on a trader's after-the-fact judgment call.