If the housing-market shakeout has an epicenter, it probably lies in Florida. For companies with business tied closely to the state, that is a problem.

During the boom, home prices around Miami and Tampa ran up faster than almost anywhere in the country. Goldman Sachs economists note that speculative buyers in houses and, especially, condos fed a building boom that pushed Florida’s housing stock up far more quickly than the state’s population grew. Now, Goldman says, investors better watch Florida’s woes carefully.

Speculators who have held back on selling now bear heavy costs. According to the U.S. Commerce Department, the number of vacant homes for sale in Florida doubled last year to 4.3 percent of the state’s total housing stock. That’s the highest vacancy rate in the country. As more speculators throw in the towel, Florida housing prices may have much farther to fall.

Home builders, hard hit everywhere, are getting hit hardest in Florida. Building permits for new-home construction — an important leading indicator of activity — were 51 percent below their year-ago level in the first quarter, according to the Commerce Department. That was twice the nationwide rate of decline for permits.

Banks with exposure to Florida real estate have been getting hurt, even some far away from the state. In April, earnings at Webster Financial, a Connecticut-based savings and loan, warned that credit quality on its Florida residential-construction loan portfolios had deteriorated.