GigaOM contributor Ucilia Wang looks at five reasons why the BrightSource IPO got pulled, from the inherent risk associated with solar to concerns about competition from cheap natural gas. Wang told me that the company waited till late Wednesday evening to officially let everyone know that the IPO was off the table. Given that shares were set to trade Thursday morning, this is particularly shocking. Investor interest must have turned tepid in a hurry, and the underwriters would have faced a load of BrightSource shares that they had to sell or carry on their own books. While I think we can blame the challenges of the solar industry for this one, I do think part of the issue here is that overall capital markets for IPOs are tight. While the number of IPOs in the first quarter was the highest since the second quarter of 2011, the total amount of money raised was a meager $5.5 billion compared to $13 billion for the first quarter of 2011. There just isn’t that much interest from investors right now in pouring money into public offerings.