Can the stock market grow faster than GDP indefinitely? My understanding of conventional wisdom is that average long-term growth of advanced economies is expected to be significantly lower than the average long-term growth of the value of the largest firms in the stock market (e.g. the total value of the FTSE 100).  I also accept Kenny LJ's argument that GDP (and the stock market) can grow exponentially, indefinitely.

But if the largest firms in the stock market, taken as a group, always grow faster, doesn't that suggest either


an unsustainable trend, or
a fundamental restructuring of the economy is in progress?


Is there any limit to how many times larger FTSE 100 firms could be than the output of the entire economy, for instance?

EDIT: To be completely clear, I am not using the FTSE as a proxy for the wider stock market or private sector more generally, so I'm pretty sure survivor (or selection) bias is nothing to do with the answer.  I am literally asking about the size of the group of the largest $x$ companies listed today relative to the total economy.
There are trends that has allowed stock markets in advanced economies to grow faster than GDP for a long time:


Branching out abroad. This gives access to faster growing markets in developing countries. This trend will end when all countries are advanced economies.
Fewer private companies. This trend will end when most of GDP is generated by companies listed on the stock market.
Multiple Expansion. Reduced interest rates and increased money supply can reduce returns expectations and increases PE multiples. This trend has worked both ways through time but for the last 10-20 years it has generally acted in an expansive capacity.


In addition, there is a way for the stock market to generate a higher return  without an increase in stock market value:


Dividends. Dividends increase stock market return without increasing its value. Though not really considered growth, dividends are often included when comparing stock market growth with GDP growth.