It’s not quite man bites dog. But it is an unusual story these days when a major company signs a major office lease expansion in Boston’s Financial District. BisNow and the BBJ have more on Klaviyo’s lease of 256K sf at 125 Summer St. …But here’s more proof that Newton’s Third Law applies to CRE too. From Bisnow: “Fidelity Puts 800K SF Boston Headquarters Up For Sublease.” B&T has more on Fidelity’s move from 245 Summer to its refurbished CommonWealth Pier.