  Ever since the web began, the number of websites has been growing
exponentially. These websites cover an ever-increasing range of online services
that fill a variety of social and economic functions across a growing range of
industries. Yet the networked nature of the web, combined with the economics of
preferential attachment, increasing returns and global trade, suggest that over
the long run a small number of competitive giants are likely to dominate each
functional market segment, such as search, retail and social media. Here we
perform a large scale longitudinal study to quantify the distribution of
attention given in the online environment to competing organisations. In two
large online social media datasets, containing more than 10 billion posts and
spanning more than a decade, we tally the volume of external links posted
towards the organisations' main domain name as a proxy for the online attention
they receive. We also use the Common Crawl dataset -- which contains the
linkage patterns between more than a billion different websites -- to study the
patterns of link concentration over the past three years across the entire web.
Lastly, we showcase the linking between economic, financial and market data by
exploring the relationships between online attention on social media and the
growth in enterprise value in the electric carmaker Tesla. Our analysis shows
that despite the fact that we observe consistent growth in all the macro
indicators -- the total amount of online attention, in the number of
organisations with an online presence, and in the functions they perform -- we
also observe that a smaller number of organisations account for an
ever-increasing proportion of total user attention, usually with one large
player dominating each function. These results highlight how evolution of the
online economy involves innovation, diversity, and then competitive dominance.
