Ad revenue optimizer PubMatic has closed a second round of funding. Draper Fisher Jurvetson, Nexus India Capital and Helion Ventures—all previous backers—participated in the round; the amount wasn’t disclosed. The new funding will go towards promoting the Palo Alto company’s plans for global expansion. One part of that is the rollout of a new ad optimizer tool, PubMatic Premier, which is targeting publishers that make over $5 million in annual online revenue. The system promises to help publishers better identify the best-performing ad networks. PubMatic says it can detect, in real-time, the highest-paying ad network to fill publisher inventory. PubMatic also says that its system can ensure that the ad nets publishers use do not compete with a site’s direct sales force—a problem illustrated by publishers’ fears of “commoditizing” their inventory—by giving publishers absolute control over the quality of the ad buys.Release