NEW YORK >> The volatile trading that defined 2015 led to a very choppy market for companies wanting to go public.

The number of U.S. companies that successfully made an initial public offering of stock in 2015 dropped by more than 40 percent compared with 2014, according to a report by IPO research firm Renaissance Capital.

The amount raised was considerably less as well, falling to $30 billion in 2015 from $85.3 billion. The drop-off was the result of significantly reduced ambitions from companies as they hit the market, as well as wariness of investors rattled by sharp swings on Wall Street, particularly in the second half of the year.

The August downturn and a U.S. market correction in September persuaded a lot of companies to put their plans to go public on hold, Renaissance Capital said.

IPO activity stalled not only in the United States, but around the world. The amount of money raised in IPOs globally was $156.2 billion, down 35 percent from a year earlier.

The industry that had the largest number of IPOs was health care, followed by energy.

The largest IPO of 2015 was First Data, which raised $2.56 billion.