Photo: Shelby Knowles for The Wall Street JournalPimco recently defaulted on a mortgage backed by a portfolio of office buildings that included Twitter’s headquarters in San Francisco. Defaults and vacancies are on the rise at high-end office buildings, in the latest sign that remote work and rising interest rates are spreading pain to more corners of the commercial real-estate market. For much of the pandemic, buildings in central locations that feature modern amenities fared better than their less-pricey peers. Some even were able to increase rents while older, cheaper buildings saw surging vacancy rates and plummeting values. Now, these so-called class-A properties, whose rents generally fall into a city’s top quartile, are increasingly coming under pressure.

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