When lower Manhattan’s new World Trade Center was conceived a decade ago, nobody had in mind a Silicon Valley in the sky.

Financial companies, which dominated the original twin towers, are scarce among tenants who have committed to space at the complex’s glass-and-steel skyscrapers. Instead, the majority of deals done since magazine publisher Conde Nast agreed to anchor 1 World Trade Center in 2011 have come from technology, media and advertising.

“People were expecting financial companies to be a substantial portion of the leased space” in the new towers, said Christopher Jones, vice president of research at New York’s Regional Plan Association. “I don’t think many people would have thought that it would be virtually nothing.”

The November opening of 1 World Trade Center, the 1,776- foot (541-meter) skyscraper built at the site of Sept. 11, 2001, terrorist attacks, marked a milestone in a lower Manhattan renaissance that’s been fueled by a changing mix of inhabitants beyond the area’s finance-industry roots. That shift is presenting a challenge: The creative companies dominating New York’s office market tend to be comparatively small, leaving landlords to fill their monumental buildings floor-by-floor.

Almost 2 million square feet (186,000 square meters) are unrented at 1 and 4 World Trade Center, the first buildings to open at Ground Zero. Agreements were signed for about 340,000 square feet in 2014, with no single lease larger than the 106,000 square feet that digital-advertising company MediaMath Inc. took in July at tower 4, according to CoStar Group Inc., a Washington-based research firm that tracks office leasing.

At that pace, the towers wouldn’t reach 95 percent occupancy until 2019, almost two decades after the 9/11 attacks leveled the first twin towers.