The New York Stock Exchange publishes end-of-month data for margin debt on the NYXdata website, where we can also find historical data back to 1959. Let's examine the numbers and study the relationship between margin debt and the market, using the S&P 500 as the surrogate for the latter. The first chart shows the two series in real terms — adjusted for inflation to today's dollar using the Consumer Price Index as the deflator. I picked 1995 as an arbitrary start date. We were well into the Boomer Bull Market that began in 1982 and approaching the start of the Tech Bubble that shaped investor sentiment during the ... (full story)