What stock-market device did Thomas Edison improve while working for Gold and Stock Telegraph?

Thomas Edison improved the stock-market device known as the universal stock ticker while working for the Gold and Stock Telegraph Company.

Stock tickers transmitted changing prices from exchanges to brokerage offices. Edison’s improvements made the machinery more reliable and helped standardize the printed symbols and operation used by financial businesses.

In 1871, the Gold and Stock Telegraph Company paid Edison for improvements to its ticker technology and employed him as a researcher. The payment helped finance his independent work and laboratory experiments.

The universal stock ticker is sometimes mistaken for Edison’s first invention. His first U.S. patent was instead for an electrographic vote recorder. The ticker was important because it was one of Edison’s earliest commercially successful electrical technologies.