Then there is the potential increase in the cost of doing business, as companies beef up security, re-examine insurance policies, and prepare to shoulder the cost of increased travel to meet with clients outside India.
Gopalakrishnan of Infosys said some clients have canceled travel plans, but others have pledged to visit soon as a sign of solidarity. "The messages I'm getting are don't worry, we want to support you in this period of tragedy," he said.
A raft of events have been canceled, including Live Earth, a concert scheduled for Dec. 7, and the Champions League Twenty20, an international cricket match scheduled for this month - taking with it lucrative advertising and sponsorship contracts.
Armando Kraenzlin, regional vice president and general manager at Four Seasons Hotel Mumbai, a luxury hotel that caters to business travelers, said it's too early to assess the full impact of the attack.
"We will be affected, of course," Kraenzlin, adding that he knew three people who were killed.
Business travel could fall by 25 to 30 percent in December, which is peak season for both tourists and dealmakers, Religare predicts.
Travelers don't always react in predictable ways to terrorism. After the Madrid bombings in 2004, U.S. travel to Spain increased 8 percent between 2004 and 2005.
Bollywood, India's Mumbai-based film industry, could also be hurt, said Komal Nahta, editor of the Bollywood trade publication "Film Information."
He fears foreign crews will think twice about filming in India, and he expects funding in the next few months to become "dear and difficult."
"Already recession has begun to take its toll on the film industry. In this kind of climate, they've got one more reason to slow down," he said. "Nobody wants to fund a project and see it going down the drain because of terrorist attacks."
Mumbai's elegant Art Deco cinemas have been eerily empty since the attacks. P.P. Murlidharan, manager of the 1,024-seat Eros cinema, not far from the Taj hotel, said attendance has been 30 percent of normal.
"Friday, Saturday, Sunday should be house full," he said. "But it is empty."
Associated Press writers Anita Chang and Ramola Talwar Badam contributed to this report from Mumbai.