 DoubleVerify, an ad-measurement and verification firm, is set to make its debut on the New York Stock Exchange on Wednesday, marking the latest of a flurry of IPOs in the digital advertising space. The US-based company is set to raise around 360 million, having priced its IPO at 27 a share. That would give DoubleVerify, which will trade under the stock ticker symbol DV, a valuation north of 4 billion. 