The fate of the European Union—and short-term the stability of global markets—may now reside in the hands of United Kingdom’s voters.

Investors are holding their breath as voters in Great Britain and certain parts of the Commonwealth of Nations decide whether the U.K. will remain part of the EU on Thursday.

Whether voters choose to leave, or “Brexit,” the EU or remain, there will be lasting implications that may take years to realize, says Tom Stringfellow, president and CIO of Frost Investment Advisors, a San Antonio, Texas-based asset manager.

“Although the results of the vote are yet to be realized, the ongoing debates point to fairly serious economic, regulatory, political and nationalist consequences,” Stringfellow says. “One of the more significant risks that could be unleashed is the threat of a further unraveling from the peripheral nations of the EU, such as Italy, Spain or Greece.”

Stringfellow cites analysis by the U.K. Treasury that estimates that a Brexit would lower the country’s GDP by 3.6 percent after two years and raise unemployment by 520,000, while launching a massive overhaul of regulations, contracts and laws.

Yet concerns over the long-term global market impact from a Brexit may be overstated, says Michael Arone, chief investment strategist for Boston-based State Street Global Advisors.

“In the short term, you’re likely to see some volatility in stocks and currencies, and in the fixed income market,” Arone says. “The brunt of the volatility will be felt in gilts, sterling and U.K. stocks, but that will probably last a short amount of time, as little as a couple of days or a week.”

Oddsmakers and polls indicate the "Remain" faction is in the lead, but the polling is close enough that it’s anyone’s guess what British voters will decide, says Arone.

While aftershocks from a vote to leave the EU could ripple throughout the global economy, Arone says that the impact could be a positive one for U.S. investors as gold, the dollar and U.S. Treasuries would enjoy a boost.

Simon Ward, chief economist at Chicago-based Henderson Global Investors, said the immediate impacts of the vote really depends on the market environment it occurs in.