Passage: The Hepburn Act, which gave the Interstate Commerce Commission (ICC) the power to set maximum railroad rates, became law in July 1906. This depreciated the value of railroad securities. Between September 1906 and March 1907, the stock market slid, losing 7.7% of its capitalization. Between March 9 and 26, stocks fell a further 9.8%. (This March collapse is sometimes referred to as a "rich man's panic".) The economy remained volatile through the summer. A number of shocks hit the system: the stock of Union Pacific—among the most common stocks used as collateral—fell 50 points; that June an offering of New York City bonds failed; in July the copper market collapsed; in August the Standard Oil Company was fined $29 million for antitrust violations. In the first nine months of 1907, stocks were lower by 24.4%.On July 27, The Commercial & Financial Chronicle noted that "the market keeps unstable ... no sooner are these signs of new life in evidence than something like a suggestion of a new outflow of gold to Paris sends a tremble all through the list, and the gain in values and hope is gone". Several bank runs occurred outside the US in 1907: in Egypt in April and May; in Japan in May and June; in Hamburg and Chile in early October. The fall season was always a vulnerable time for the banking system—combined with the roiled stock market, even a small shock could have grave repercussions.

Question: What is the March collapse called sometimes?
rich man's panic