“A stock is measured at one specific time, and represents a quantity existing at that point in time (say, December 31, 2004), which may have accumulated in the past. A flow variable is measured over an interval of time. Therefore, a flow would be measured per unit of time (say a year)” [1].
Equity value is a stock metric. GDP is a flow. Put another way, Germany outputs about one NVIDIA every year. (The total value of the German stock market is about €3tn. A better comparison would be that NVIDIA and Anthropic are worth as much as all of Germany’s public equity.)