  In this paper we refer to the Open Web to the set of services offered freely
to Internet users, representing a pillar of modern societies. Despite its
importance for society, it is unknown how the COVID-19 pandemic is affecting
the Open Web. In this paper, we address this issue, focusing our analysis on
Spain, one of the countries which have been most impacted by the pandemic.
  On the one hand, we study the impact of the pandemic in the financial
backbone of the Open Web, the online advertising business. To this end, we
leverage concepts from Supply-Demand economic theory to perform a careful
analysis of the elasticity in the supply of ad-spaces to the financial shortage
of the online advertising business and its subsequent reduction in ad spaces'
price. On the other hand, we analyze the distribution of the Open Web
composition across business categories and its evolution during the COVID-19
pandemic. These analyses are conducted between Jan 1st and Dec 31st, 2020,
using a reference dataset comprising information from more than 18 billion ad
spaces.
  Our results indicate that the Open Web has experienced a moderate shift in
its composition across business categories. However, this change is not
produced by the financial shortage of the online advertising business, because
as our analysis shows, the Open Web's supply of ad spaces is inelastic (i.e.,
insensitive) to the sustained low-price of ad spaces during the pandemic.
Instead, existing evidence suggests that the reported shift in the Open Web
composition is likely due to the change in the users' online behavior (e.g.,
browsing and mobile apps utilization patterns).
