There are many different types of investors in ad tech including corporations, venture capital, institutions like hedge funds and pension funds, individuals, family offices, and government/education. The document discusses understanding the various sources of finance and buyers in the ad tech market, as well as how ad tech fits into the broader tech context compared to the UK/European media sector. It also reviews public market multiples and performance, M&A activity in 2019, and the digital advertising market while touching on data and GDPR issues.