On Thursday morning, Chuck Robbins, the chief executive of Cisco, signed on to a companywide video conference from his home office in Silicon Valley. The connection was stable, but the quality was not great.

“I tell you,” he said in an earlier interview, “this whole teleworking thing — as much as we sell it to our customers, I’m not sure I want to do it 100 percent of the time.”

In addition to Mr. Robbins, the video conference featured several mental health professionals, who spent an hour answering questions from Cisco employees grappling with the stress of working from home during the coronavirus outbreak. “Nobody prepares for this,” he said.

Cisco, which makes networking equipment, has seen demand for its Webex video conferencing system spike. In response, it has redeployed teams to focus on making sure big customers can conduct everyday chats and board meetings remotely.

Still, it is a stretch. “None of this technology was designed to support the entire world working from home,” Mr. Robbins said. “The Webex teams haven’t slept in days.”

As the coronavirus sweeps the globe, even chief executives — who normally flit from meetings to conferences in chauffeured SUVs and private jets — have been confined to spare rooms.

From there, they are working to keep their business afloat as the stock market plummets; managing supply chains upended by travel restrictions and labor shortages; and trying to keep their employees healthy and sane.

‘It’s a Miracle You Can Run a Company This Way’: Sundar Pichai of Alphabet

At an undisclosed location in Silicon Valley, Sundar Pichai, the chief executive of Alphabet, has a very nice home office. Soaring ceilings. Artfully decorated two-tone bookshelves. A seating area. A really big plant. It’s the kind of home office you would expect the wealthy chief executive of one of the world’s most powerful technology company’s to have.

From there, Mr. Pichai is monitoring the myriad ways that Alphabet — which includes Google, YouTube and more — is responding to the coronavirus crisis. Paramount among his concerns, he said, is ensuring that disinformation is kept in check.

“We’re making sure that most of the information is coming from expert organizations and journalistic organizations, and are trying to surface them higher across all our products,” he said via a Hangouts video call.

At the same time, Google is seeing a spike in demand for its G-Suite and Hangouts products, and has most of its employees working from home as well. “It’s a miracle you can run a company this way,” he said.

Mr. Pichai, like so many, is also having to navigate the home front. “The day-to-day juggling of all this stretches all of us,” he said. “It was not easy to help my teenage daughter to understand what is going on.”

‘It Is a High Stress Environment Right Now’: Adena Friedman of Nasdaq

Adena Friedman, the chief executive of Nasdaq, made the decision weeks ago: Key personnel at the stock exchange would be split into two teams.

Each week, one team would work from home and the other would work from the office. Over the weekend, the office would be cleaned. In the event that one team got sick, the other team could run the company.

During her rotations away from the office, Ms. Friedman has been working from her primary residence in Chevy Chase, Md. — along with her husband and two sons, both in their 20s, all of whom are also working from home.

Ms. Friedman follows the same routine each workday. She wakes up at 5:30 a.m., rides on her Peloton, eats breakfast and gets to work. During the day, she is monitoring the steady decline in the markets, trying to ensure that banks — which also have most employees working remotely — are clearing trades, and taking meetings with executives who are also at home.

“What’s been really fun is to peer into the personal lives of your colleagues,” she said in a telephone interview. “Sometimes a kid will walk into the room. My dog has been barking all day.”

When Ms. Friedman gets hungry, she runs downstairs and makes herself a peanut butter and honey sandwich, then races back to her office for more calls. “It is a high stress environment right now,” she said.

‘All Hands From The Laundry Room’: Stewart Butterfield of Slack

For Stewart Butterfield, the chief executive of Slack, it was bad time to have spotty internet service. He was stuck at home in San Francisco amid the shelter-in-place orders last week, and had an all-company video conference to host. But with his home internet wonky because of construction, there was just one room that had a decent connection. “I did the all-hands from the laundry room,” he said in a telephone interview.

Slack, the messaging company, has experienced a sharp spike in usage in recent weeks, as much as 30 percent above previous highs of messages sent per day. “We’ve seen an incredible surge in new sign-ups that has tracked pretty closely to the countries that have been affected,” he said.

Mr. Butterfield contends the new demand has galvanized the team. “It was probably the most productive week of work in the company’s history,” he said.

But Mr. Butterfield said he was aware that it might not last. “The adrenaline rush eventually wears off,” he said. “We don’t want people to burn out.”

‘It Feels Very Strange’: Albert Bourla of Pfizer

Albert Bourla, the chief executive of drugmaker Pfizer, was happy when the bickering began. His college-aged daughter had moved back home to Scarsdale, N.Y., after the coronavirus closed schools around the country, and she was already at it with her mother.

“I had missed the fights between my wife and my daughter,” he said in a telephone interview. “I’m happy to see it once more. The day starts with a fight and ends with a fight.”

When not delighting in his reunited family, Mr. Bourla is grappling with the immensity of the challenges confronting Pfizer, a global company that is also a critical cog in the health care system. “My mind right now is spinning a thousand times,” he said. “It’s not only that I feel responsible for the 90,000 people of Pfizer. I feel a responsibility to bring a solution to this crisis.”

Pfizer is ramping up production of medicines that might be needed to treat patients suffering from Covid-19, the disease caused by the novel coronavirus. It has also begun aggressive research into a vaccine for the virus, as well as antiviral treatments.

Mr. Bourla saw the crisis coming somewhat earlier than others. Pfizer’s offices in Asia were affected by the coronavirus months ago, and Mr. Bourla said the novelty of remote working quickly wore thin for workers there. “After a couple of weeks there was a fatigue of working from home,” he said. “It feels very strange.”

‘I Don’t Have All The Answers’: Gregg Renfrew of Beautycounter

Gregg Renfrew, the chief executive of Beautycounter, was trying to work from an apartment in the Pacific Palisades neighborhood in Los Angeles, but her husband kept interrupting her video calls.

Beautycounter, a private company that makes makeup and shampoos, doesn’t sell through stores. Instead, it does most of its business through a network of consultants — mostly women — who sell to their friends and associates.

Ms. Renfrew has been trying her best to manage the disruption wrought by the coronavirus — fortifying her supply chain, increasing the production of some essential items and postponing some product launches. But the pressure to keep the company running is intense at a time when many small business owners are facing an existential crisis.

“I have 50,000 people whose livelihood depends on us,” she said in an interview via Zoom. “And I have to acknowledge that I don’t have all the answers.”

Last week, in recognition that everyone was feeling a bit frazzled, Ms. Renfrew told company employees to take Friday off. “We all need to figure out how to manage everything,” she said. “Then we can come back and get to work.”

‘We’re Starting a Daily Mental Health Call’: Marc Benioff of Salesforce

On a conference call the other day, Marc Benioff, the Salesforce chief executive and co-founder, made an insensitive remark. Describing how the company was meeting customer demand during the coronavirus crisis, he said, “We have a full Chinese menu of options for our customers.” The blowback was swift, with employees around the country reprimanding him via email.

“I am learning new levels of sensitivity,” Mr. Benioff said via FaceTime from his home office in San Francisco, where he is holed up amid the region’s shelter-in-place order.

Mr. Benioff apologized, but the gaffe wasn’t particularly surprising. Like most of his 50,000 employees, he is juggling professional demands and personal life from home.

Mr. Benioff, already a rampant networker, said the volume of inbound communication he is receiving surpasses anything he has experienced before. “It’s everything from working with our management team to planning the fiscal year,” he said. “I’m having to adjust what my priorities are.”

Also: His father-in-law is staying with him, and his mother comes over for dinner every night. To cope, Mr. Benioff, a Buddhist, has been meditating more.

Salesforce employees are also feeling the strain. Mr. Benioff said an internal survey revealed that 36 percent of his work force was experiencing mental health challenges these days. “And those are the ones who are willing to admit it,” he said. “We’re starting a daily mental health call, to encourage daily prayer meditation and mindfulness.”

‘We All Have to Make Trade-Offs’: Giovanni Caforio of Bristol Myers Squibb

Giovanni Caforio, the chief executive of the drugmaker Bristol Myers Squibb, was monitoring the coronavirus long before most Americans. Mr. Caforio is Italian, and his brother, who works in a hospital in Rome, told him weeks ago that the virus was serious. “I know firsthand three people in the I.C.U.,” Mr. Caforio said in a telephone interview. “Two in Milan and one in Rome.”

Now Mr. Caforio is running the company from his home in Princeton, N.J., where his wife and two children are also trying to keep up with their responsibilities. His wife manages a nonprofit that provides food to the underprivileged. His college-aged son came back from Scotland after school was canceled. And his daughter is a senior in high school. “She is not getting a prom or a graduation ceremony,” he said. “We’re adapting to a new reality.”

Mr. Caforio said Bristol Myers Squibb’s supply chain, which is sourced from the United States and Europe more than China, was holding up well so far. But he acknowledged that new disruptions were possible as the virus spreads around the globe. Some hospitals in Europe have started already started stockpiling Bristol Myers Squibb’s products in anticipation of supply constraints.

Mr. Caforio knows it is a stressful time, and is trying to be empathetic with his work force. “Some of our employees working from home were feeling almost guilty,” he said. “They were struggling about how to balance their personal needs with how to help the company. It’s OK. Right now we all have to make trade-offs.”