In 1990, Salomon Brothers found a way to push past a limit in the U.S. Treasury auction system. The limit was 35%. No single bidder could receive more than 35% of the securities offered to the public. Then came the December 27, 1990 auction of $8.5 billion of four year Treasury notes. Salomon bid $2.975 billion for itself exactly 35%. But it also submitted an unauthorized $1 billion customer bid. Combined: 46% of the entire offering. The customer bid was ultimately transferred to Salomon. And this wasn’t an isolated incident. Salomon later admitted to unauthorized bids in five Treasury auctions between December 1990 and May 1991. The scandal triggered investigations by the Treasury, SEC, Federal Reserve and Congress. The SEC later alleged that Salomon had repeatedly submitted false bids to circumvent Treasury’s purchase limits. Here’s the part traders should remember A market rule doesn’t automatically create a level playing field. The real game includes understanding Who the rule applies to. How it is calculated. What counts as one bidder. What happens when participants try to work around it. That’s not a lesson about “breaking rules.” It’s a lesson about market structure. If you’re trading a market, don’t just learn its price patterns. Learn the rules that determine how the game itself is played.