Tesla Inc. took a step toward financing its transformation from a niche builder of pricey luxury cars to a mass-market rival of Fords and Chevrolets, setting plans to raise $1.5 billion in its first-ever sale of traditional bonds.

The electric-car maker, gearing up for an ambitious expansion with the introduction of its more moderately priced Model 3 sedan, is expected to sell the bonds as early as Friday in a deal underwritten by Goldman Sachs Group Inc.

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