The collapses of Silicon Valley Bank and Signature Bank this past weekend were the end point in an all-too-familiar cycle: first the boom, then the breathtakingly speedy bust and then the bailout. We are now at the postmortem moment — when everyone wonders where the regulators were.

Silicon Valley Bank has already become notorious for how obvious its red flags were. Perhaps the most telling was the rapid growth of its borrowing from the Federal Home Loan Banks system. Banking experts know this Depression-era group of government-sponsored lenders as the second-to-last resort for banks. (The Fed is, as always, the lender of last resort.) At the end of last year, Silicon Valley Bank had $15 billion of FHLB loans, up from zero a year earlier.

“That’s the type of flag that says you need to look closely,” Kathryn Judge, a Columbia law professor who specializes in financial regulation, told me. But there’s no sign the loans triggered any regulatory attention.

Primary responsibility for the debacle lies, of course, with SVB’s management. But regulators are supposed to grasp that they exist because bankers are always tempted to take risks. Bankers want to grow too fast, borrow cheaply, lend freely and lock their investments up unwisely for long periods in hope of gaining higher returns.

Some commentators are now reiterating calls for banking rules to be tightened, which is probably a wise move. But the collapse of the two banks proves once more that the culture of the regulators is as important as any rules, laws or tools at their disposal.

At least one journalist detected banks’ rising vulnerabilities, including those of Silicon Valley Bank, as early as last November; the Federal Deposit Insurance Corp.’s own chair had also warned about the problem. A few short sellers even started betting against the bank’s stock. Now, however, the combination of reckless bankers and lax regulators has left us with a financial crisis and a federal-government bailout — and the well-rehearsed spectacle of regulators promising to do better next time. (And yes, this was a bailout. Some depositors were facing losses and the federal government, backed by the public, prevented that — at as-yet-unknown scale and cost.)

One troubling aspect of this particular collapse is just how unremarkable a bank run it was, how basic its causes were. Regulators didn’t need any fancy analysis to detect the danger at Silicon Valley Bank. They just needed to notice its financial results. Granted, in 2018 Congress had loosened the post-global-financial-crisis Dodd-Frank regulations that would have required a bank like SVB to undergo more frequent stress tests, but those tests measure exotic or extreme risks. All that was required in this case was regular supervision. The bank had clear risk-control flaws and disclosed losses on its books, right there in its Securities and Exchange Commission filings.

Silicon Valley Bank’s assets had grown dramatically, quadrupling in five years, as had its deposits. Both phenomena are almost always worrying signs. The bank was also overly concentrated in one sector of the economy, and an unusually large proportion of its deposits — about 94% — was uninsured, above the $250,000 limit that the FDIC will guarantee per deposit.

No bank can survive if every creditor asks for their money back at once. The larger the portion of a bank’s clients that could wake up one day to realize that their deposits are not protected, the greater the risk of a run.

What Silicon Valley Bank did with those deposits should have been another warning signal. It used them to buy too many long-term bonds. As interest rates go up, bonds lose value. Nobody should have needed the warning, but the bank itself said that interest-rate risk was the biggest hazard it faced. And regulators should have noticed before the bank began borrowing heavily from the FHLB system.

In its SEC filings in the third quarter of last year, the bank’s parent company disclosed that it was sitting on losses from its bond purchases big enough to swamp its total equity. That would have been a good time for supervisors to tell the bank to get its act together.

Silicon Valley Bank was far from doing so: It hadn’t had a chief risk officer for most of that year. “Regulators had to know that, and it has to matter,” Jeff Hauser, the founder and director of the Revolving Door Project, a Washington nonprofit that tracks the regulatory state, told me. “Once we valorize success as proof of wisdom, it’s hard for a lowly bank examiner to say, ‘This place doesn’t have a risk officer and doesn’t have a plan to address the risk on its books.’”

Bank regulators have awesome powers. They can go into a bank, examine its operations and demand changes. The problem is that they rarely do. “The regulators are like all the conflicted agents in ratings [agencies] and other areas,” Chris Whalen, a longtime financial analyst, told me. “They go with the flow in good times and drop the ball in bad times.”

The San Francisco Fed, which regulated the parent company, and the California regulators, which oversaw the bank itself, could have required SVB to raise capital last year, when it was less vulnerable. They could also have required the bank to increase rates on its savings accounts — in other words, to pay people more to lend it money. That would have eroded earnings but it would’ve kept customers from fleeing. Ask Greg Becker, the bank’s chief executive, today if he would rather have reduced per-share earnings or avoided having superintended the second-largest banking collapse in U.S. history.

So why don’t we have regulators who can be relied on to do their jobs?

Part of the answer is a legacy of the Trump administration’s penchant for installing regulators who are opposed to regulation. Donald Trump appointed Randal Quarles as the first-ever vice chair of banking supervision at the Federal Reserve. (The Fed did not respond to questions for this story.) Quarles saw it as his mission to relax the post-financial-crisis regime. He sent unambiguous signals about how he felt about aggressive regulators — “Changing the tenor of supervision will probably actually be the biggest part of what it is that I do,” he declared in 2017. Translation: Any sign of showing teeth and he’ll get out the pliers. And when Jerome Powell was nominated to be the chair of the Fed, in 2017, he told Congress that Quarles was a “close friend,” adding, “I think we are very well aligned on our approach to the issues that he will face as vice chair for supervision.” Naturally, Quarles supported the 2018 law to roll back stress tests — something that Becker himself had called for. Quarles also did not respond to my request for comment.

This crisis raises the old issue of how strange it is that the Federal Reserve regulates banks at all. In the years leading up to the 2008-09 financial crisis, an alphabet soup of regulators ostensibly shared responsibility for banking oversight along with the Fed: The OTS (Office of Thrift Supervision), the OCC (Office of the Comptroller of the Currency), the SEC (Securities and Exchange Commission), and the CFTC (Commodity Futures Trading Commission). Banks and financial entities played these agencies off against one another to shop for the least restrictive. Policy makers and legislators knew this and toyed with changing the architecture of banking-and-securities regulation. Ultimately, their only action was to close down the least of them, the OTS, and keep the rest, each of which had its own constituency of supporters.

So the Federal Reserve kept its responsibilities. But critics argue that the Fed can never become an effective bank regulator because its chief concern is with the more glamorous business of managing the economy.

The roots of regulatory failure run deeper, however, than the Trump administration’s actions. President Joe Biden’s appointees at the Federal Trade Commission, the Department of Justice, and the Consumer Financial Protection Bureau appear to be trying to wield their powers to make the economy more efficient, safer and more equitable. But pockets of learned governmental helplessness remain. Regulators have an ingrained fear of stepping in, making people uncomfortable, making demands and using their clout.

The Fed’s banking supervisors should have been on heightened alert as its governors started boosting interest rates. Silicon Valley Bank faced not only the interest-rate risk to its treasury-bond holdings but also the likelihood of credit losses accumulating on its books from distressed venture-capital firms and declines in commercial real-estate values last year.

The fact that the Fed supervisors weren’t agile with Silicon Valley Bank indicates that they have failed to internalize how woefully fragile our financial system is. The U.S. has suffered repeated bubbles, manias and crashes since the deregulatory era began under Ronald Reagan: the savings-and-loan crisis, Long-Term Capital Management, the Nasdaq crash, the global financial crisis, the financial convulsions of the early pandemic. Congress and regulators sometimes shore up aspects of the system after the event, but they have failed to foster a resilient financial system that doesn’t inflate serial bubbles. Each time, instead, the regulators reinforce a lesson that if bubble participants huddle as closely together as possible, and fail conventionally, the government will be there to save them.

“One of the most disturbing dynamics here,” Judge, the Columbia Law professor, told me, “is a loss of respect for the Fed as a supervisor, as a regulator.” That is not a good place for the industry’s chief overseer to start rebuilding confidence in the integrity of the American banking system.