The U.K. has voted to leave the European Union, and all hell has broken loose in the world's financial markets.

Even though the polls showed a close race, most of the pundits and so-called experts were confident that the Brexit option would be voted down.

The fundamental lesson of this latest crisis is that anything can happen, so never rely on the assurances and the predictions of the establishment.

Once investors find out how dumb the "smart money" is, it is too late. To have any hope of accumulating enough money to retire, find a way to guarantee returns now.

Here are three stocks that meet two crucial criteria: the nature of their business insulates them to some extent from the turbulence in Europe, and they have a proven track record of generating reliable returns.

1. Dominion Resources (D - Get Report)

This company has been a solid investment for many years. It is one of the nation's largest producers and transporters of energy, with a portfolio of about 23,600 megawatts of generation.

Dominion Resources also operates one of the nation's largest natural-gas storage systems, with 947 billion cubic feet of storage capacity.

The utility serves retail energy customers in 10 states, with the majority located in North Carolina, Virginia and West Virginia, a region that has seen considerable growth in recent years and will likely continue to do so.

The stock had a rough first quarter, as the market overreacted to the company's loss of a federal grant for some wind demonstration projects. But it has been trending upward of late and testing a key resistance level on the upside.

As investors fly toward safe industries such as utilities, the stock is set for big gains.

2. FedEx (FDX - Get Report)

The company has largely replaced the Post Office as the key institution for moving packages around the United States. The dynamism of a private company is always a good bet against a sclerotic government bureaucracy.

The Memphis, Tenn.-based company's acquisition of Kinko's a few years back has yielded positive results and some welcome diversification to its revenue stream.

Recently, FedEx reported adjusted net income fiscal fourth-quarter earnings of $3.30 a share, up from $2.66 a year earlier, higher than most analysts' estimates. Revenue for the quarter rose 7.4% to $13 billion, also higher than expected.

3. Tetra Tech (TTEK - Get Report)

The company provides consulting, engineering and technical services to energy, environmental, infrastructure, natural-resources and water industries.

Tetra Tech depends largely on government contracts for its revenue stream, which will help insulate it from the ups and downs of the markets.

This week, the company said that the National Guard Bureau has awarded it a $45 million contract to provide architectural and engineering design services to support projects including master planning, value engineering studies, and facility design. The firm has been winning contracts like this for more than 15 years, and with governments shoveling money at green-energy initiatives, it looks like a good bet for the future.

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We are only halfway through 2016, and there have already been a whole series of events that the smart money said could never happen, from the rise of Donald Trump to the triumph of Brexit. In this unpredictable world, investors must guarantee their financial futures. So check out this special report that allows investors to win on at least 85% of trades, money-back guaranteed. Click here for a free copy.

See full Brexit coverage here.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.