NEW YORK, Nov 29 (Reuters) - The number of S&P 500 companies that have either stopped political giving or plan to disclose it hit a record in 2021 after the Jan. 6 attack on the U.S. Capitol and recent social justice protests, according to a study viewed by Reuters. According to the study from the Center for Political Accountability, U.S. companies see new risks in political giving in light of the country"s hyper-partisan environment, leading corporations to either halt contributions or disclose them. The center advocates for corporate transparency. "Unrest and angry political conflict have defined the past two years," according to the study, which cited as examples the violent assault on the U.S. Capitol, the two-time impeachment of former President Donald Trump and attempts to overturn the 2020 election. "In these explosive times, companies are taking action. "They’ve adopted political spending policies to avoid or mitigate heightened risk," according to the study. Political spending came under closer scrutiny earlier this year after a raft of major companies suspended contributions to lawmakers who voted against President Joe Biden"s election certification. L1N2JN2ZQ At the same time, some companies, such as Delta Air Lines Inc (DAL.N), are becoming outspoken on social and political issues, including voting rights. L1N2OP2UL The new study found that 370 companies disclose some or all of their political spending, or ban at least one type of it, such as contributions to trade associations. That figure is up from 332 companies last year. L1N2H31BW The Center for Political Accountability considers disclosure or outright banning of political giving a mark of top flight corporate governance policy, said Bruce Freed, the group"s president. The study found that one of the biggest changes over the past six years among companies related to so-called "dark money" groups, which are tax-exempt organizations that influence politics. There was nearly a 100% increase from 2015 to 2021 in the number of companies who prohibit or disclose contributions to those organizations. Intel Corp (INTC.O) was highlighted by the study for adopting a corporate political contribution policy stating that the chipmaker reviews recipients" voting records and public statements, and that it will communicate directly with them. The study also highlighted videogame maker Activision Blizzard Inc (ATVI.O) and artificial intelligence computing company NVIDIA Corp (NVDA.O), among others, for improving their policies by prohibiting payments to the "dark money" groups.