Calhoun's personal financial situation deteriorated significantly and swiftly after 1906. He claimed he lost $2.5 million ($ in dollars) in the 1906 San Francisco earthquake, and that he'd been ruined by adverse publicity. He also spent heavily on strikebreakers in a 1907 streetcar strike, and incurred significant legal expenses fighting the streetcar workers' union. In 1912, an investigation by the California Railway Commission found that Calhoun had concealed a $1.2 million ($ in dollars) loss in his San Francisco company in order to keep the stock price high. His investors forced him to resign the presidency of the United Railways of San Francisco in the summer of 1913.