Insurance giant AIG startled markets last week when it signaled its waning faith in the euro by moving tens of millions of dollars worth out of the currency zone, reducing its holdings in banks in Germany, France, Spain and Italy.

The news came on the heels of a similarly unsettling announcement by International Airlines Group, the parent company of British Airways, which said Aug. 3 that it had reduced its exposure to Spain and formed a committee to prepare for the worst-case scenario of Spain exiting the euro zone.

The one-two punch is the latest in a series of efforts by corporations, central banks and individuals to move money out of crisis-stricken euro-zone countries as the debt crisis envelops an ever-larger part of the continent.

Such currency moves are bets on the future of national economies. The recent capital flight, analyst say, is a vote of no confidence in the euro that some worry could snowball into a series of silent bank runs. If institutions and consumers lose faith in the euro, a massive flight could lead to economic collapse.

“People are not frantic yet, but the concern is increasing and they are thinking, ‘How can I protect myself?’ ” said Enrico Cantarelli, a former adviser to the Italian treasury department who is a managing partner of Phinance Partners, a financial consulting firm.

Smaller firms are also reassessing their exposure. In Rome, Davide d’Atri, chief executive of Soundreef, a start-up that collects royalties on behalf of recording companies from music played in stores and other public venues, said his company’s finances could be devastated if the value of the euro were to drop further. So he has opted to keep most of the company’s cash in British pounds rather than euros. “We don’t have any control of this, and you want control of your finances,” he said.

Uneasiness about the future of the single currency has weakened the euro against nearly all the 16 counterparts in recent months. It is down about 4 percent against the U.S. dollar this year.

Capital flight has been at the root of the European financial crisis since it began more than two years ago. In the beginning, the issue was mostly a reshuffling of money within the euro zone, such as investors moving assets from smaller, troubled countries such as Ireland, Portugal and Greece into more stable euro-zone countries such as Germany.

Starting around July 2011 — when it became clear that some of the larger economies such as Spain and Italy were also in danger — the pace accelerated as investors shed a broader range of euro-zone investments.

Now money is starting to leave the euro zone altogether, said Jens Nordvig, a managing director at Nomura Securities who researchers currency and bond issues.

Nordvig said that in the past two months he has seen echoes of what happened in Mexico and Indonesia when their currencies began to collapse in the 1990s: “This is something very serious to watch, because if this type of dynamic escalates, it really will make the situation look like an emerging market currency crisis.”

It’s impossible to get a comprehensive picture of international money flows, but estimates of the amounts involved are staggering.

Citigroup’s Matt King has calculated that capital outflows from Italy and Spain in 2011 totaled 160 billion and 100 billion euros respectively, or 10 percent of the countries’ gross domestic product. King, global head of credit products strategy for Citigroup, said that the situation in Italy seems to have stabilized in recent months but that the rate of capital flight from Spain continues to be in the range of tens of billions of euros a month. That pace, King said, “is ominous.”

Separately, a study published in April by Central Banking Publications, a London research firm, found that nearly a third of 54 central banks surveyed had reduced their euro holdings in the past 12 months. Even more said they planned on selling euros in the coming months.

Those shrinking holdings are also reflected in International Monetary Fund data. In the first quarter of 2012, euros represented 24.9 percent of central banks’ allocated reserves, down from 27.3 percent in the same period of 2010, according to the IMF.

Indeed, Michael Derks, chief strategist for FxPro, a currency-trading firm based in London, said that in the past six to eight weeks, he’s seen deposits moving out of relatively strong euro-zone countries to places that don’t use the euro, such as Britain.

“A lot of French nationals are turning up in London right now and Germans and Dutch who are high net worth investors, and they are looking to diversify some of their wealth out of the single currency,” Derks said. Their assets are being moved into British pounds, U.S. dollars, Swiss francs and Japanese yen, he said, with some “bits and pieces” going to other currencies such as the Norwegian krone and Australian dollar.

Derks said he thinks the current rate of outflows is just the beginning: “This process of moving money out of Europe — not just by high net worth investors but also by sovereign wealth funds and corporate treasurers — still has some way to run.”

Fearing massive outflows of capital, European regulators have begun talking openly about ways to restrict the movement of money should Greece or another country leave the euro zone.

In Switzerland, where the Swiss franc has become a popular investment for those worried about the euro, the central bank has said it may limit foreign deposits. The Swiss franc has seen a sharp rise in value that is threatening the competitiveness of Swiss exports. The Bank of England, meantime, has been discussing whether to impose taxes on foreign inflows to limit appreciation of the pound.

While traditional capital control measures, such as imposing quotas or shutting down automated teller machines, are restricted within the 17-country euro zone, governments and financial institutions have been taking less draconian steps to slow down the movement of money. (Some of these measures are aimed as much at stopping tax evasion as stemming the flight of capital.)

Spain has banned cash business transactions over 2,500 euros, while Italy is requiring paperwork for all cash purchases over 1,000 euros. Some Portuguese banks are trying to reduce the outflow of money by requiring that large transactions be done in person, in hopes that the inconvenience will discourage hasty action.