A major oil spill will result in cleanup spending that boosts GDP, but no one thinks oil spills are good. Oil spills and other forms of pollution are examples of negative externalities — harm caused to others by the economic activity of a firm or industry. These externalities represent a failure of the market, and unless there is corrective action, their presence means that there is too much production of something that causes negative spillovers.

That criticism can be applied to the financial services industry. Many say that it grew too large, triggered a financial crisis and damaged the rest of the economy. Is that still the case, and is financialization spoiling the economy? Despite the alarmist rhetoric around today’s finance sector, the answer is generally “no” because of changes made to financial regulation.

First, a check on the facts: How large is the industry and how much has it grown? The broad definition of the financial sector includes finance, insurance and real estate, known by the acronym “FIRE.” It was 17.5 percent of gross domestic product in 1990 and rose to 20.0 percent in 2014, but that figure is misleading as it includes office and apartment rents and leases — stuff that has little to do with Wall Street.

Finance and insurance separately peaked well before the financial crisis at 7.7 percent of GDP, which was up from 5.8 percent in 1990. In 2014, it was 7.0 percent of GDP. Employment in finance and insurance has been on a downtrend since 2003 and is currently 4.25 percent of total nonfarm payrolls. Most of those jobs are in offices and bank branches around the country. (The output data given here are drawn from the Bureau of Economic Analysis, GDP by Industry data. The employment data are from the Bureau of Labor Statistics, Payroll Employment data. Author’s calculations.)

Still, salaries and bonuses at the top are extremely attractive, so perhaps the externality plays out by drawing the best and brightest away from other more productive activities. The Harvard Crimson reported that in 2007, 23 percent of graduating Harvard seniors said they planned to enter finance. That is an impressive number, but things turned around sharply, with the 23 percent figure falling to 11.5 percent in 2009 after the financial crisis. At this point, the financial industry really isn’t large enough to crowd out other parts of the economy.

Meanwhile, the insurance industry serves an important social purpose providing life, property, and casualty insurance. AIG got into trouble in the crisis because it strayed into providing very risky financial services, not because of its main insurance business. Likewise, the core value of banks is financial intermediation between savers and investors, giving savers relatively secure and liquid assets while also funding investment.

There are critics of how well our banking industry serves this core purpose, a quality that is hard to determine. My judgment is that it does the job pretty well compared to most other countries. As the IMF reported in September 2015, the non-performing loan problem among European banks remains severe, whereas most U.S. banks now have strong balance sheets. Good financial intermediation means that most of the savings dollars are transferred to investors and are not lost through inefficient bank operations. A 2002 study that I participated in found bank productivity higher in the United States than in France or Germany.

The parts of the financial sector that give rise to the most concern are market-making, deal-making and the creation and trading of derivatives on Wall Street. The volume of market trading has increased exponentially because of the increased speed of computers and communications. Up to a certain point, the increased volume is helpful because it adds to the liquidity of markets, but the advent of high-frequency trading has taken us over the top. As Michael Lewis describes in his book Flash Boys, the high speed traders are finding ways to shave milliseconds off the time needed to make trades. That is thoroughly wasteful. As for deal-making, it has been going on for a long time — indeed the go-go years for deals were in the 1980s — so it is hard to blame the recent slowing of economic growth on this activity.

Still, the explosion of derivatives and other overly-complex instruments was problematic, and it is crystal clear that the mortgage market became too opaque and removed accountability from the system. The layering of complex derivatives on top of lousy mortgages (and other shaky assets) distorted the economy, resulted in the overbuilding of houses, and caused the financial crisis. There are plenty of people at fault besides the bankers, but the smart people on Wall Street were driving the process, and they should have known better. The excessive financialization obscured the reality of loans that depended upon ever-rising home prices and thus were never going to be paid back. There was an externality because the private calculations of potential profit ignored the risks being imposed on society.

Is that still the situation today? No. Things have changed. Banks and other financial institutions that create risks for the whole economy are now required to hold sufficient capital to cover losses even in periods of economic and financial stress, plus a liquidity buffer (they must pass “stress tests” administered by the Federal Reserve). The screws have been turned pretty tight, and the owners of large financial institutions will bear the costs of future failures — not taxpayers. This brings private incentives in line with the public interest, getting rid of the externality that gave us too much financialization in the first place. But to keep the future safe, we’ll have to make sure no one forgets what happened in the last crisis, and ensure that new risks are not created in other, less-regulated parts of the industry.

Editor’s note: This piece originally appeared in the Washington Post.