San Francisco and Santa Clara County are two of the hottest commercial real estate markets in the region, if not the nation. Last month, Google, headquartered in Mountain View, leased 1 million square feet of office space (reported price, $600 million) in Redwood City. Cloud storage company Box is taking a 334,000-square-foot office building going up on the former Malibu Grand Prix site in Redwood City as its new headquarters and subleasing its old headquarters in Los Altos. RingCentral, a cloud phone vendor, is moving into an 84,000-square-foot space in Belmont, and Rakuten, a fast-growing Japanese e-commerce company, just signed a lease for 57,000 square feet in the city of San Mateo. “There are others out in the market looking for space, between 12,000 and 1 million square feet,” said Bob Garner, executive managing director at commercial real estate broker Newmark Cornish & Carey in San Mateo. Ground is being broken next week on the first of five office buildings totaling up to 1.5 million square feet in a development dubbed Bay Meadows Station 4. When completed, on a date to be determined, the “urban village” will house up to 1,250 residential units, retail outlets, 18 public parks, a community garden and open space. Neither Thacher nor Garner, whose firm is the project’s leasing agent, would disclose the names of potentially interested tenants, but said there is already quite a bit of “activity.” Commercial real estate is seeing “dramatic rent increases and a wave of speculative development not seen in years,” according to Colliers International’s third quarter real estate report. “Speculative development” means proceeding with a project on unused land, assuming its value will increase. Wong wanted to relocate Reddit’s headquarters from San Francisco’s South of Market district to a new Class A office building in Daly City ($45 per square feet), right off Interstate 280, and a couple of blocks from BART.