Snap is going public: its filing shows widening losses and slowing user growth, calling into question its ability to reach profitability and justify the ~$20 billion valuation it is seeking

Long term, the company hopes to capture the large brand advertising budgets it expects will leave TV as linear viewing declines. But how it plans to do so is unclear, as it has shown little interest in connected TVs, and the ad model for augmented reality – Snap’s focus – is a long way off

Most of all, investors are being asked to trust in the ability of Snap’s founders – who will retain full control of the company – to continually innovate products which will attract users and advertisers

Amazon’s marketing services bring in a growing stream of direct, high-margin revenue, but their main role is still in supporting vendor partnerships

Amazon uses customer profile data to profit from its own media and that of others, illustrating the value of a direct customer relationship in online advertising

In the future, Amazon’s moves into video content and voice interfaces are likely to significantly expand ad inventory, but maintaining the trust of shoppers is not straightforward