For the first time in over 10 months, the stock market is showing signs of fatigue. It's a drop in the bucket compared to the index's gains since the March 2020 bear-market bottom, but it's a potentially stern reminder that a stock market crash or double-digit correction could be around the corner. According to data from market analytics company Yardeni Research, there have been only three instances since the beginning of 1995 where margin debt jumped 60% or more in a single year.