Information Barriers and Wall-Crossing
How firms physically and procedurally separate people who might receive material nonpublic information from people who trade, and the deliberate, logged process for temporarily crossing that separation.
Prerequisites: MNPI Controls in Research
Picture a fund that both trades public equities and occasionally participates in private deals — say, providing financing to a company before it goes public. The team working on that private deal will, in the ordinary course of their job, learn things about the company that the public market doesn't know yet. If that information ever reached the desk trading the company's public stock, even accidentally, it would be insider trading. An information barrier — often just called "the wall" — is the set of controls that keeps that from happening: separate systems, separate physical or virtual spaces, and rules about who can talk to whom about what.
The wall isn't just a policy document; it's enforced through concrete mechanisms. People on the private, "restricted" side of the wall have their access to trading systems cut off or heavily monitored. Their communications with the public-trading side are restricted or logged. Securities they've learned sensitive information about get added to a restricted list that blocks the public desk from trading them, regardless of whether anyone actually crossed information — the list itself is the safety margin.
Sometimes, though, the firm legitimately needs someone from the public side to get involved in a private matter — to bring their expertise to evaluate a deal, for instance. That's where wall-crossing comes in: a deliberate, approved, and logged process for temporarily moving a person from the public side to the restricted side. It's not something that happens by wandering into the wrong conversation. It requires sign-off from compliance, a clear record of exactly what information the person is being given access to and when, and — critically — restrictions on that person's own trading (and often the desk's trading in related securities) for as long as they remain "over the wall" and for some period after.
The discipline here is less about any single rule and more about the mindset: material nonpublic information isn't something a firm tries to avoid learning — it's routinely necessary for parts of the business — but it has to be contained, tracked, and never allowed to leak into a trading decision without an explicit, logged, and time-bounded crossing.
An information barrier separates people with access to material nonpublic information from people who trade, using restricted-access systems, monitored communications, and a restricted-securities list. Wall-crossing is the deliberate, compliance-approved, logged exception that lets someone move between the two sides temporarily — never an informal or accidental event.
The classic failure isn't a dramatic leak — it's an informal one: a casual conversation in a hallway or a shared calendar invite that quietly gives someone on the public side visibility into a private deal, with no wall-crossing process ever triggered because nobody framed it as "crossing" anything.
Further reading
- Federal Reserve SR 11-7, Guidance on Model Risk Management