Moisés Naím / Bloomberg Businessweek

If you want to understand the shifting balance of power in the world economy, it helps to know the names Jorge Paulo Lemann, Carlos Brito, and Frederico Curado. Lemann, Brazil’s richest man and the dealmaker behind the $52 billion InBev-Anheuser-Busch merger and the $3.3 billion purchase of Burger King (BKW), has just teamed up with Warren Buffett to acquire yet another major American company, H.J. Heinz (HNZ), for $23 billion. Brito, the Brazilian chief executive officer of Anheuser-Busch InBev (BUD), has launched a $20 billion takeover bid for Mexico’s Grupo Modelo (GPMCY)—the maker of Corona beer—and in the process prompted a U.S. antitrust suit. (AB InBev already sells almost one in five beers in the world.) And Curado, the CEO of Embraer (ERJ), the world’s third-largest commercial planemaker, recently inked a $4 billion deal to supply American Airlines with regional jets.

These Brazilian tycoons represent a new breed of emerging-market entrepreneurs who are introducing unprecedented competition into every sector of global business. Emerging-market countries are now home to more than 1,000 companies with annual sales above $1 billion. Foreign direct investment from developing and transitional economies has outpaced FDI from rich countries for more than a decade.

It’s by now widely understood that power is flowing from north to south and west to east, from old corporate behemoths to agile startups. But to say that power is shifting from one continent or country to another, or that it’s dispersing among many new players, tells only part of the story. Nor is it enough to attribute these shifts to the impact of the Internet and other disruptive technologies.

Instead, the very nature of the power once wielded by established companies and the people who run them has changed. Rival CEOs continue to fight for dominance, but corporate power itself—the ability to influence the way consumers, competitors, and markets behave—is decaying. The Brazilian billionaires who now control multinational giants such as AB InBev are no less vulnerable than the more familiar names they’ve replaced. In the 21st century, power is easier to get but also harder to use and easier to lose.

To many people this trend may seem surprising. In the age of Occupy Wall Street and “too big to fail,” it’s unquestionable that income is concentrating and some are using money to gain political clout. Yet even the 1 Percent in the U.S. aren’t immune to sudden shifts in wealth. For all the rise in income inequality, the Great Recession also had a corrective effect, disproportionately affecting the incomes of the rich. According to Emmanuel Saez, an economics professor at the University of California at Berkeley, the economic crisis caused a 36.3 percent drop in the incomes of the top 1 percent of earners in the U.S., compared with an 11.6 percent drop for the remaining 99 percent. In 2012, Forbes said the top take-away from its list of the world’s billionaires was “churn,” with almost as many list members losing wealth (441) as gaining it (460).

Corporate chiefs may earn much more than before, but tenure at the top has become more precarious. In 1992 a U.S. Fortune 500 CEO had a 36 percent chance of retaining his job for the next five years; in 1998 that chance was down to 25 percent. According to management consultant John Challenger, the tenure of the average American CEO has declined from close to 10 years in the 1990s to about five and a half years. The position of executives in other countries is just as tenuous. In 2011 alone, CEOs at 14.4 percent of the world’s 2,500 biggest listed companies left their jobs.

The same goes for corporations themselves. A study by economists Diego Comin and Thomas Philippon showed that in 1980 a U.S. company in the top fifth of its industry had only a 10 percent risk of falling out of that tier in five years; two decades later, that likelihood had risen to 25 percent. In finance, banks are losing power and influence to nimbler hedge funds: In the second half of 2010, in the midst of a sharp economic downturn, the top 10 hedge funds—most of them unknown to the general public—earned more than the world’s six largest banks combined. Multinationals are also more likely to suffer brand disasters that clobber their reputations, revenues, and valuations, as companies from BP (BP) to Nike (NKE) to News Corp. (NWS) can all attest. One study found that the five-year risk of such a disaster for companies owning the most prestigious global brands has risen in the past two decades from 20 percent to 82 percent.

In some respects, these are heartening developments. Just as the decay of power in politics has undermined authoritarian regimes, in business it has curtailed monopolies and oligopolies while giving consumers more choices, lower prices, and, in some cases at least, better quality. Even areas in which monopolies were once thought unavoidable, such as utilities, can now be opened to competition. Cultural barriers are increasingly irrelevant: To cite just one example, Alejandro Ramírez, a young entrepreneur from Morelia, Mexico, is one of the leading players in the cineplex business—in India. Ramirez’s company, Cinépolis, began as a one-screen movie house in the 1940s in provincial Michoacán state. It’s since become the largest cineplex company in Mexico and Central America and is now seeking to meet India’s demand for modern multiplexes—there are only about a thousand modern film screens for more than 1.2 billion people—by adding 500 screens in the next few years.

The growing power vacuum also entails dangers. It’s nurtured all manner of improvised groups, companies, and media outlets that evade traditional scrutiny and whose sponsors hide in the cacophony of the Web. It’s also created more opportunities for fraud and deceit. When power is harder to use and keep, and it spreads to an ever-larger, ever-shifting cast of small players, forms of competition that threaten the social good and the survival of industries (overly aggressive business tactics designed to bankrupt rivals rather than maximize profits, for instance) are more likely to arise.

We can’t anticipate the many changes that will flow from power’s ebb, but we can adopt a mind-set that will minimize its more harmful effects. The first step is resisting elevator thinking, the obsession with who’s going up and who’s coming down. You can rank competitors at any given time by their assets, power, and achievements. But the picture this offers is ephemeral and misleading. The more we fixate on rankings, the more we risk ignoring or underestimating how much the waning of power is weakening all the competing parties, not only those in apparent decline.

We must also recognize that the decay of power creates fertile soil for those who seek to exploit the proliferation of actors, opinions, and proposals in ways ultimately counter to the public interest—consider the Wall Street wizards who championed toxic financial instruments as creative solutions. Devising enforceable safeguards to protect the public will become essential for policymakers worldwide.

In business and politics, the end of power carries risks as much as it presents opportunities. When national and international leaders are, like Gulliver, tied down by thousands of micropowers, they’re less able to address the most pressing issues of the day—from climate change to economic crises to nuclear proliferation. The fundamental challenge before us is to welcome the advances of plural voices and innovation without driving ourselves into a crippling paralysis.