AONE

Two start-ups, biofuel maker Codexis and solar-energy firm Solyndra, recently filed, and others are rumored to be doing so, including sexy electric-car company Tesla Motors and smart-grid integrated-technology maker Silver Spring Networks.

The busiest week of initial public offerings since 2007 is turning out pretty mixed. Investors gobbled up shares of an unprofitable car-battery maker, but showed little love for financials looking to make bets in the troubled commercial real estate sector. A123 Systems (AONE) generated the most...