Central Banks Are Stuck in a Rinse-and-Repeat Cycle of Crises

Central banks may be accidentally subsidizing government borrowing through their efforts to prevent a repeat of past market blowups, and policymakers are starting to worry that anticrisis lending facilities could even be interfering with their own monetary policy.

The source of the problem is the switch from central banks being the lender of last resort to, in 2008 and 2020, also being market makers of last resort, ensuring corporate—and government—debt markets keep functioning. During a crisis, support is often essential to prevent a downward spiral that destroys the financial system.

But backstopping markets removes a key risk and encourages more borrowing—especially for the hedge funds that now own trillions of dollars of U.S. Treasurys.

“Ironically, vulnerability is created by mechanisms that were introduced to reduce vulnerability,” said Huw Pill, the Bank of England’s chief economist, one of those growing concerned, in an interview. “So, it’s a bit like a whack-a-mole kind of story.”

Offering either an explicit or implied guarantee that government-funding markets will remain open and liquid means hedge funds have less risk of being unable to finance highly leveraged trades. This is particularly true for the overnight repurchase, or repo, market, where borrowers pledge bonds for cash. The result has been a huge expansion of two popular government bond trades, arbitraging Treasurys or British gilts against bond futures or swaps.

The scale is extraordinary: The Dallas Fed estimates hedge funds ended last year with $2.4 trillion of Treasurys, up from $600 billion a decade earlier. Because the profits on each trade are tiny, hedge funds have to leverage as much as 100 times to get worthwhile returns, creating new risks.

This might sound abstruse. But in 2020, it was the Treasury basis trade blowing up that forced the Fed to intervene. In 2025, signs of trouble in the swap trade pushed President Trump to retreat from his tariff plan.

Pill worries that the reassurance central-bank policy provides bleeds into monetary policy by boosting borrowing. This, in turn, keeps government-debt yields lower than they otherwise would be.

“There’s lots of gilts to be bought,” he says. “How do you support that buying of gilts? You make it attractive. How do you make it attractive? Well, there are some imperfections in the market. So those imperfections create profit opportunities, but they’re not very big. So how do you make them more meaningful? You allow leverage to build up.”

“That’s good for the government because it gets to sell the gilts at a lower [yield] than it otherwise would. It’s good for the financial sector because they’re able to extract these rents effectively. And it’s good for the central bank because the market seems to be liquid and functioning. But all of those things are true until they’re not true.”

When it goes wrong, the more leverage, the worse the problem. And the worse the problem, the more likely it becomes that central banks have to create yet more special tools to address it. That then spurs the next buildup of leverage.

Pill thinks more effort is needed to come up with a modern version of the Bagehot Doctrine. Walter Bagehot, the 19th-century editor of the Economist magazine, summed up the role of the central bank as being to lend to banks freely, against good collateral, at a penalty rate. Access to instant cash helps banks withstand runs. The fact the central bank is offering a backstop should make the run less likely, and shareholders are penalized, through the penalty rate, if it is used.

English economist and journalist Walter Bagehot. Hulton Archive/Getty Images

Tools for saving markets from drying up are more haphazard. In 2020 the Fed, BOE and others just bought lots of government debt to inject liquidity into markets. That worked because, even though quantitative easing is also a monetary policy tool, they also wanted easier money.

Unfortunately, that created what Pill described as a tinderbox, ignited by the energy crisis after Russia invaded Ukraine. The excess money creation from left over from emergency QE then fanned the flames of inflation. This made it much harder to calibrate monetary policy when central banks decided to tighten (although policymakers were also, in my view, far too slow to recognize inflation).

Pill points to the “temporary, targeted” BOE buying of gilts amid the forced selling by leveraged pension funds after Britain’s botched tax-cut plan in September 2022 as a successful model. At a time when the BOE was trying to tighten monetary policy, it intervened in a way that stopped the pension fund selling spiral and stabilized gilts. Yet the central bank maintained tight monetary policy.

Bagehot would recognize the goal: Reduce the encouragement to take risk, known as moral hazard, that offering guarantees in advance creates, but retain the ability to mount a rescue in a crisis.

Unfortunately, much of central banking is going backward on this. Moral hazard is increasing, even for banks. In the 2023 bank bailout, the Fed accepted less-than-full collateral, recognizing Treasury bonds at face value rather than their (much lower) market value.

The emergency rescue facility then became a funding facility that even healthy banks chose to tap—in effect easing monetary policy by the back door and prompting the Fed to tighten the terms before it ended. Something similar could be under way with Japan’s plans to use an emergency Fed loan facility to raise cash to prop up the yen without having to sell its hoard of Treasurys.

I don’t know how to break the cycle of crises needing rescues that lead to more leverage and new crises. And I’m concerned we’re firmly into the added-leverage phase of the latest cycle.

At least central bankers are still thinking about it, even if they don’t, so far, have good answers.

Wall Street’s hottest trade has gone ice cold.

For years, it paid off to buy stocks that were rising in price—and bet against struggling shares. The momentum trade was especially profitable this year, as investors piled into hot stocks including Micron Technology, Nvidia, Advanced Micro Devices and other artificial-intelligence darlings while wagering against those likely to be hurt by the embrace of AI.

The S&P 500 Momentum Index soared 44% in the second quarter, its best quarterly performance on record, and it surged 133% over the past five years, nearly double the broad market’s performance.

Mega funds and rookie investors alike piled into the trade, some using leverage and options contracts in an effort to amplify their returns, propelling the underlying shares higher.

“It is a self-fulfilling prophecy,” said Matthew Tym, managing director at Cantor Fitzgerald, of the trade.

Suddenly, the trade is a loser. The momentum index has tumbled more than 9% since July 1, lagging behind the S&P 500’s 2.8% gain. The index—which tracks stocks in the S&P 500 based on a “momentum score”—is on track for the biggest quarterly underperformance in 25 years. July was the second-worst month for the momentum trade in around 40 years, according to Bank of America estimates; the only month worse was April 2009, in the teeth of the global financial crisis.

Hedge funds that bought momentum shares while shorting low-momentum stocks suffered even more. At the same time, a basket of the most popular stocks held by hedge funds tracked by Goldman Sachs recorded its biggest one-month underperformance in July relative to the S&P 500 in more than 20 years, according to the bank’s analysts.

Momentum trading is based on a rather simple observation: Investments that go up tend to keep outperforming; those that underperform often remain laggards. This kind of trading might seem too simple a stock-picking strategy to work. Yet it often has.

“For decades, it didn’t take a lot of sophistication to run a momentum strategy and make a decent living at it,” says Agustin Lebron, senior researcher at EquiLibre, a trading firm.

Part of the reason: It takes a while for corporate and other information to spread to various investors, so they slowly build positions, producing buying momentum.

“A huge pension fund can’t flip around its positions in a day,” says Lebron. “Behavioral biases also account for some of the effect, as well—people tend to sell their winners too early and hold losers too long.”

Fans of the strategy point to the human tendency to extrapolate from past results—and chase investment returns—noting that momentum patterns have been evident in markets for decades, even centuries. They also say that some of the worst months for momentum strategies are during longer periods of outperformance.

Some have been doing the trade by buying the strongest investments in a sector while shorting the weakest; others lean in to rising markets or asset classes. Still others use a quantitative approach or turn to banks or others who sell ways to make distinct wagers on momentum as a “tradable factor” or a “thematic basket.”

The fans remain believers. “Any strategy has disappointing periods,” says Antti Ilmanen, global co-head of the portfolio solutions group at AQR Capital Management.

The surge in Moderna and other biotech stocks helped crush the momentum trade. These shares were among the most heavily shorted in recent years, but positive news on a cancer vaccine from Moderna and Merck sent those stocks flying, crushing some quant and other hedge funds. Moderna is up around 150% so far this month.

These traders had an especially rough day on Aug. 19, which Goldman Sachs told its clients was the worst day for “systematic long-short managers” in more than two years. About half of the losses were because of momentum trades, the bank said.

Some traders have begun to short, or bet against, the very stocks that propelled the momentum trade earlier this year. Net short positions in futures tied to the Nasdaq-100 index among speculators recently climbed to some of the highest levels of the past two decades, according to data from the Commodity Futures Trading Commission.

The about-face is a sign of how markets have become more treacherous for investors, even as indexes keep climbing. Part of the issue: the recent meltdown of Situational Awareness, a hedge fund that had piled into some of the most popular momentum shares, including chip stocks. After a period of market tumult, Nvidia shares rocketed almost 9% after its earnings, showing how quickly sentiment can shift.

Some investors say the run-up in share prices driving tech stocks higher reminds them at times of the dot-com frenzy decades ago.

Mike Ogborne, the founder of San Francisco-based Ogborne Capital Management, said he has grown more cautious on technology stocks and is keeping more of his portfolio in cash than he typically does.

And he is nervous about the surge in spending by technology giants and quarterly capital expenditures that keep rising.

“It is a little bit like Cinderella and the clock striking midnight. You don’t know when midnight is going to come around,” Ogborne said. “They don’t send a memo around telling you when the capex cycle is over.”

Central Banks Are Stuck in a Rinse-and-Repeat Cycle of Crises

Wall Street’s hottest momentum trade has reversed sharply, as former winners tumble and heavily shorted stocks surge.