"Sell the loser, book the loss, save on taxes" is one sentence and three constraints. Do it well, across a whole book, without tripping a wash-sale window or drifting from the index, and harvesting stops being a screen and becomes the constrained optimization it actually is. That is the problem PRISM was built to solve.
In a taxable account, a harvested loss is a genuine, spendable benefit: it offsets gains and, within limits, ordinary income. A fund cannot pass an individual security's loss to you; an account holding the securities directly can. That is the entire economic case for direct indexing. But the naive approach — periodically sell whatever is down and buy a placeholder — leaks the benefit in a dozen quiet ways: it books losses the wash-sale rule will later disallow, ignores which lots to sell, and drifts the portfolio off its benchmark. Each leak is small; across a book and a year, they are the difference between a program that markets well and one that delivers the after-tax dollars it promised.
Doing it properly means treating harvesting as an optimization that maximizes after-tax value subject to tracking error, the wash-sale envelope across the household and across time, lot-level holding-period rules, and turnover and cost limits — all at once, because they are coupled. We wrote about exactly why this is hard →
PRISM is a black box with a clean contract: your positions, lots, constraints, and benchmark in; optimized, wash-sale-aware trades and a reproducible audit log out.
Maximizes after-tax value subject to all the coupled constraints — for every account.
The 61-day envelope is respected across the household and across time — no quietly-disallowed losses.
Which specific shares to sell is treated as the decision it is, with holding-period awareness built in.
Harvesting stays inside your tracking-error budget — you capture the loss without abandoning the index.
PRISM does not claim to beat the exact single-account optimum every time. Its edge is capturing tax alpha that simpler approaches structurally miss, and doing it at a scale exact methods cannot reach. Comparators are labeled generically.
Share of tested regimes where PRISM delivers more after-tax wealth. An open-source baseline captures only ~$3k at scale where PRISM captures six figures.
Share of tested regimes where PRISM beats rules-based harvesting on after-tax wealth.
Names at which PRISM is the only engine measured still producing six-figure tax alpha.
A matched-workload pilot runs harvesting on your accounts and constraints and shows the after-tax result against your current approach — every losing case included, ROI computed with your numbers.
Request a pilot →