Big banks in the United Kingdom have scrapped payouts to shareholders this year. So have many European banks. But across the pond, the top boss of the biggest bank in the United States by assets is still thinking about it.

JPMorgan Chase & Co's chief executive Jamie Dimon said in his annual letter to shareholders published on Monday that he sees a "bad recession" in 2020, and that the bank could suspend its dividend payouts to shareholders if the coronavirus crisis deepens.

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Dividends - payouts to shareholders - deplete bank capital reserves which they need as a cushion against bad loans. And there could be a tsunami of loan defaults in the pipeline as the new coronavirus shutters businesses around the US, throwing millions of people out of work.

Bank regulators in the UK and Europe have already pressured banks under their watch to cut dividends. But the US Federal Reserve has not made the same request of US banks.

It is estimated that some two-thirds of payouts the largest US banks make to shareholders come in the form of "share buybacks" - basically using profits to buy back shares of a bank to artificially boost the value of those left in circulation. The eight largest US banks, including JPMorgan Chase, have voluntarily suspended all share buybacks through July 31, saying they wanted "to provide maximum support to individuals, small businesses, and the broader economy through lending and other important services".

Dimon, widely regarded as the face of the US banking sector, is the most prominent voice on Wall Street so far to project that the economic cost of the coronavirus will not evaporate quickly, and said the bank's earnings would be down "meaningfully in 2020".

JPMorgan could look at suspending dividends if economic growth were to fall by as much as 35 percent in the second quarter and the unemployment rate were to rise further to 14 percent in the fourth quarter of the year, Dimon wrote in his annual letter to shareholders.

"If the board suspended the dividend, it would be out of extreme prudence and based upon continued uncertainty over what the next few years will bring," Dimon said.

Dimon, who returned to work last week after undergoing emergency heart surgery in March, highlighted several other challenges that the bank is facing, saying its call centres have struggled in the current environment, with many of them effectively shutting down due to local restrictions.

JPMorgan will extend benefits to customers hit hard by the health crisis, by introducing measures such as waivers for late fees and a 90-day grace period for mortgage and car loan payments, according to the letter.

Dimon also said that the vast majority of the bank's 16,850 ATMs were "well-stocked and still functioning" to provide cash for customers.

The bank said it had extended about $950m in new loans to small businesses and would still extend credit to small businesses.

"In both our central case scenario for 2020 results and in our extremely adverse scenario, we are lending - currently or plan to do so- an additional $150bn for our clients' needs," Dimon said.

Even with that lending, Dimon wrote JPMorgan currently has over $500bn in total liquid assets and $300bn in incremental borrowing capacity from the Federal Reserve and Federal Home Loan Banks.

Dimon did not pass up the opportunity to suggest regulatory and fiscal policy reform, as he has often done in past annual letters.

"After the crisis subsides (and it will), our country should thoroughly review all aspects of our preparedness and response. And we should use the opportunity to closely review the economic response and determine whether any additional regulatory changes are warranted to improve our financial and economic system. There will be a time and place for that - but not now."