“Can policy makers fill the gaps in their knowledge about the financial system?” you ask (“The Great Unknown,” January 15, 2011). I very much doubt it. As you point out, “there was a bewildering list of financial exotica that played a significant rôle in the meltdown.” Indeed. The International Monetary Fund and the Financial Stability Board, a global club of regulators, will be none the wiser about the financial exotica even if all the data they now want is collected and maintained on a regular basis. Another meltdown will surprise them sooner or later. One of the reasons for this is not lack of knowledge, but transactions bordering on criminal activity. The recent probes into the international financial system have unearthed much that is unsavory already. What the global club of regulators needs is an undercover arm along the lines of the Federal Bureau of Investigation or Central Intelligence Agency. This is the only plausible way to deal with the financial exotica of the most pernicious kind. In the absence of an undercover arm, regulators will forever be plagued by the gaps in their knowledge.