Speaking at the Reuters Global Investment Outlook 2020 Summit, several investors said, however, they were not too worried by a potential Warren presidency because many of her plans would struggle to pass what is likely to be a divided Congress.

"Her policies scare the heck out of every wealthy guy I know," said Mike Novogratz, CEO of Galaxy Digital, which invests in cryptocurrency and blockchain. But he added: "They don't scare me as much because I don't think they're practical." Novogratz has donated to Warren's rivals, including South Bend, Indiana Mayor Pete Buttigieg.

While cool on the U.S. senator from Massachusetts specific policy proposals, several donors and investors credited her political savvy, financial knowledge, and agreed that policymakers needed to confront rising income inequality or face long-term adverse social and economic repercussions.

But many questioned whether Warren's proposals would successfully address these issues, saying they feared her plan to fund trillions of dollars in social projects through a range of taxes could have unintended adverse consequences, such as reducing economic growth or dampening the stock market.

"Senator Warren is saying things that are difficult to enact, and I don't know how you end up paying for them," said Marc Lasry, chairman at Avenue Capital Group, who has donated to several of Warren's opponents for the Democratic nomination.

Wall Street's antipathy for Warren will help more moderate and conservative alternatives, including former New York City Mayor Michael Bloomberg, who is expected to file for the Alabama Democratic presidential primary to keep his options open for a possible presidential run, a source familiar with the matter told Reuters on Thursday.

The Warren campaign did not respond to a request to comment.

Warren, who is seeking the Democratic nomination to face Republican President Donald Trump in the November 2020 election, has long made it clear she has little regard for Wall Street and many wealthy investors have much to lose if she is successful. Buoyed by grassroots funding, she has been able to snub the corporate coffers that have backed many presidential campaigns and propose policies that would squeeze the wealthy.

She has outlined a new tax of at least 2% on households whose net worth tops $50 million as well as a charge of 0.1% to sell stocks or bonds. She also wants to break up big banks, big tech and increase regulation on private-equity companies.

The Democratic senator has also proposed spending $20.5 trillion on a Medicare for All healthcare plan and several trillion more to make public colleges free, cancel some student loan debt, combat climate change, build affordable housing and increase social security benefits for retirees and other groups.

Reuters/Ipsos polls of Democratic-leaning voters put Warren at about 11% nationally, more than double her share in April, though still behind former Vice President Joe Biden and U.S. Senator Bernie Sanders.

Several investors also questioned Warren's plan to push Americans to a government-run healthcare plan, instead of private health insurance. Glenn Hutchins, co-founder of private equity firm Silver Lake, argued instead for creating a government-run system that people could choose, or keep their private insurance.

The current chairman of investing company North Island and part-owner of the Boston Celtics basketball team has given largely to Democrats, including presidential contenders John Delaney, Kamala Harris and Steve Bullock, as well as former U.S. Representative Beto O'Rourke, who recently dropped out of the race. He said his policy is to donate if asked and that, while he had contributed to Warren's Senate campaign, he did not expect to be solicited during her presidential run.

"It's a very good thing that they have a bunch of people out there making their case," he added.

Some investors and strategists, though, said they saw opportunities to profit from a massive government spending plan.

"Almost all federal spending - of any sort, on anything - tends to be stimulative," said Anne Mathias, a strategist at fund manager Vanguard. "Whether you spend it on healthcare or you spend it on defense or you spend it on highways, the sheer act of borrowing money from the market and spending it can be stimulative to the economy."

By Trevor Hunnicutt