Coronavirus economic updates: Markets close flat after Monday's steep rally

The coronavirus pandemic has quickly evolved from a health crisis to a financial one, shuttering businesses, upending entire industries and sending financial markets reeling.

Here's the latest news on how the COVID-19 crisis is affecting the economy. For more on financial resources available during the pandemic, click here.

Here's how the day is unfolding. Please refresh for updates.

Twitter co-founder pledges $1 billion from his equity in Square to combat COVID-19

Twitter CEO and co-founder Jack Dorsey announced he is giving $1 billion from his equity in the mobile-payment platform he founded, Square, to help "fund global COVID-19 relief."

The $1 billion of his equity in Square represents approximately 28% of his wealth, Dorsey said. After the pandemic is over, the focus of the donation will shift "to girl's health and education, and UBI," he wrote, referring to a universal basic income.

"Why now? The needs are increasingly urgent, and I want to see the impact in my lifetime," Dorsey wrote in a tweet. "I hope this inspires others to do something similar. Life is too short, so let's do everything we can today to help people now."

He set aside the funds in an LLC that he formed, called "Start Small," and is allowing all money movements through the new foundation to be tracked publicly online.

US financial markets closed relatively flat after Monday's steep rally

U.S. financial markets ended Tuesday's session slightly lower after a steep rally on Monday.

All three major indices closed down by a fraction of a percentage point, with the Dow Jones Industrial Average down 0.1%. The S&P 500 was down 0.2% and the Nasdaq slipped 0.3%.

Optimism that the number of U.S. cases has flattened spurred a steep rally on Wall Street to kick off the week. On Monday, the Dow closed up 1,627 points or 7.7%. The S&P 500 spiked 7% and the Nasdaq was up 7.3%.

On Tuesday, U.S. Surgeon General Jerome Adams told "Good Morning America" that the pandemic has already begun to plateau in some places.

"The good news is that when you look at Italy, when you look at Spain, when you look at Washington and California, and even New York and New Jersey, they have truly started to flatten their curves," he noted. "They've seen cases level off and start to come down, and that's what I want people to understand -- that it's going to be a hard and tough week, but the American people have the power to change the trajectory of this epidemic if we come together like we have after past tragedies in this country."

'Pharma-bro' Martin Shkreli seeks temporary release from prison to 'assist in research work on COVID-19'

Martin Shkreli, the disgraced former pharmaceutical industry executive who gained notoriety for hiking up the price of a life-saving drug, is seeking a temporary release from prison to assist in COVID-19 research.

Shkreli did not make a formal application to federal court in Brooklyn where he was convicted of securities fraud, but wrote about seeking a three-month "furlough" from prison in a scientific paper posted by Prospero Pharmaceuticals Tuesday.

"I am asking for a brief furlough (3 months) to assist in research work on COVID-19. Being released to the post-COVID world is no solace to even the incarcerated," Shkreli wrote.

He added that he believes he is "one of the few executives experienced in ALL aspects of drug development" and will do the work unpaid.

TSA screening levels at the 'lowest since the days after 9/11'

In another signal that the outbreak has clobbered the air travel industry, the U.S. Transportation Security Administration said Monday a record low number of travelers were screened at checkpoints nationwide.

The agency screened only 108,310 travelers on Monday, compared to 2,384,091 on the same day last year.

A TSA spokesperson told ABC News, "It's safe to say it's the lowest since the days after 9/11."

Delta announces plans to give away 200,000 pounds of food

As demand for air travel plummeted amid the pandemic, Delta announced Tuesday it plans to donate more than 200,000 pounds of food to hospitals, food banks and other organizations.

The airline announced it had cut back its service offerings on board and at Delta Sky Clubs in an effort "to reduce touchpoints between customers and employees."

"As a result, Delta has been left with food that would have expired before it could be served to customers," the company said in a statement.

It added that its employee teams are engaging with organizations that can immediately use the food, and "efforts to identify and support organizations globally will be ongoing as we maneuver through these unprecedented times."

In Georgia, food has been donated to the Georgia Food & Resource Center and in Missouri to the state's Carthage Crisis Center. ​

In Nice, France, Delta said it donated prepackaged snacks to hospitals and health care workers.

ABC News' Aaron Katersky contributed to this report.