Complex sentence: Sotheby's is a multinational corporation, originally British but now owned and headquartered in New York City, that is one of the world's largest auctioneers of fine and decorative art, jewelry, and collectibles.
Split into simpler sentences: Sotheby's is a multinational corporation, originally British but now owned and headquartered in New York City. It is one of the world's largest auctioneers of fine and decorative art, jewelry, and collectibles.