The firm builds and runs its own technology. It exists to support research, market analysis, portfolio monitoring, and risk, and it is used only inside the firm.

Systems that gather and organize the material research is done on, so a document, a figure, or a series can be found and read against its source rather than against a copy of it.

Positions, the exposure they carry, and the conditions each was taken under are held together and reviewed on a fixed schedule rather than when something moves.

A bought system encodes the assumptions of whoever built it: what counts as a comparable, which adjustments are standard, what a figure means when a filing is ambiguous. Those are research decisions, and a firm that accepts a vendor’s answers to them has outsourced part of its process without deciding to. The firm builds its own so that the assumptions in a number are the firm’s own and can be changed when the reasoning changes.

Judgment. The systems gather, organize, and check; they do not decide. A position produced by a model that no one could argue from first principles would be a position the firm could not defend when it moved against it, and defending a position under pressure is the only time the reasoning behind it matters.