European Central Bank policymakers surprised Thursday with a bigger-than-expected boost to their pandemic emergency bond-buying scheme, adding 600 billion euros and extending it until mid-2021.
"The envelope for the pandemic emergency purchase programme (PEPP) will be increased by 600 billion euros ($674 billion) to a total of 1.35 trillion," an ECB spokeswoman said.
The emergency scheme will be extended to "at least the end of June 2021" rather than December this year, she added, or until the ECB's governing council "judges that the coronavirus crisis phase is over".
Governors also agreed to reinvest the proceeds from their PEPP purchases "until at least the end of 2022", saying that any future winding-down of the massive expansion in the ECB balance sheet would be "managed" to avoid disruption to financial markets.
ECB President Christine Lagarde will detail the thinking behind policymakers' decisions at a 1230 GMT press conference.
She will also present formal growth and inflation forecasts from central bank staff, after warning last week that the eurozone economy could contract by between eight and twelve percent this year.
After initially shocking markets early on in the pandemic by downplaying the need to step in, the ECB has made massive interventions in the eurozone economy to keep up access to credit for companies, households and governments.
Pictet Wealth Management strategist Frederik Ducrozet highlighted the importance of reinvesting the proceeds from bonds held by the central bank.
"It should allow the ECB to deviate more, and for longer, from capital keys," he tweeted, targeting its support to individual countries rather than rigidly buying bonds in line with member nations' share in the ECB's capital.
Such signals may be more important to markets than the headline increase in bond-buying, as the bank was unlikely to exhaust its ammunition anytime soon at its present purchase pace.
"The strong signal can bolster the nascent rebound in the confidence of households and companies that the worst will soon be over," said Berenberg bank economist Holger Schmieding.
Hints at further action could come in the ECB's inflation forecasts, as the central bank's main task is to ensure price stability in the 19-nation eurozone.
Price growth slowed to just 0.1 percent year-on-year in May from 1.2 percent in February before the pandemic and well below the ECB's target of close to, but just below two percent.
Meanwhile, the euro's growing strength against the dollar is creating a headwind for exports.
Governors met Thursday less than a month after a German Constitutional Court (GCC) ruling that a two-trillion-euro bond-buying scheme launched in 2015 may not have been "proportionate" to its price stability goal and needed to be clarified.
If the ECB cannot satisfy the judges, the German Bundesbank central bank may not be able to participate in bond-buying.
While finding a face-saving solution to the immediate legal headache, policymakers must also consider how court challenges might limit their future options.
With Thursday's decisions, "the ECB is also demonstrating that it remains a truly independent institution fully committed to its mandate of price stability -- and is not in any way constrained by the verdict," Berenberg economist Schmieding said.