Oscar, a health insurance start-up, valued at $1.5 billion

Sixteen months after going live, the insurance company Oscar has joined the elite group of start-ups known as unicorns, or those with billion-dollar valuations. The company plans to announce on Monday that it has raised $145 million from a group led by the billionaire Peter Thiel and his Founders Fund venture capital firm. Other investors in the round included the Hong Kong billionaire Li Ka-shing's Horizon Ventures, the Wellington Management Company and Goldman Sachs. The investment values Oscar at about $1.5 billion, more than three times its valuation last January.