Financial news traveled by telegraph wire then printed in morning papers. A London statement took 3 days to reach New York traders. Information was scarce and power concentrated in those who had it first.
Nathan Rothschild received news of Wellington's victory at Waterloo nearly a full day before the British government did — via a network of private couriers and carrier pigeons. The wilder versions of the legend (that he shorted and then cornered the bond market that afternoon) are exaggerated. The underlying fact — a private actor with a better information network outpacing the state — is the original version of the entire timeline.
A failed attempt by a copper magnate to corner the United Copper Company stock triggered the collapse of Knickerbocker Trust, one of New York's largest. The run spread to other trust companies inside 48 hours. No Federal Reserve existed. There was no lender of last resort. A full-blown banking crisis could only be stopped by private coordination, which is what happened.
John D. Rockefeller told a reporter that sound stocks were cheap and that he personally was buying. The quote ran in the morning papers. That alone was enough to stabilize sentiment across a market where, at the time, the word of one wealthy private citizen could effectively substitute for a central bank's statement.