Moments ago, WSJ reported that venture-backed transportation company Uber said it had raised $1.2 billion in additional funding from investors that valued the on-demand car service at $18.2 billion, among the highest valuations ever for a venture-backed startup.

The eye-popping valuation, following weeks of competitive bidding among mutual-fund managers and venture-capital firms, underscores investor interest in the so-called sharing economy, where users sell time or resources to others. Uber connects drivers and riders through a smartphone app. It also highlights many investors' belief that Uber can expand the service into the backbone of a logistics and delivery network.

The latest funding round was led by three mutual-fund managers: Fidelity Investments, which invested about $425 million; Wellington Management, $209 million; and BlackRock Inc., $175 million. Four venture firms also participated, according to a person familiar with the matter: Summit Partners; Kleiner Perkins Caufield & Byers; Google Ventures, and Menlo Ventures.

One scary observation: when mutual funds such as Fidelity start allocating funds to start ups, one may want to re-evaluate just how bubbly the market isn't.

Another scary observations: at $18.2 billion, Uber has more than quadrupled its valuation in less than a year. Per the WSJ only Facebook . in 2011 raised capital at a higher valuation from private investors—an investment from Goldman Sachs valued the social network at $50 billion—according to VentureSource data.

One final observation: at $18.2 billion, Uber has a valuation which according to CapIQ is higher than 254 companies in the S&P500, or more than half; it also has a higher valuation than all the companies in the Russell 2000!

What else is there to say.

Here are some companies whose valuation was just surpassed by Uber: