No labor ever was embedded into the stock, and it's freely exchanged without ever being consumed. It's not an unused store of value because it exists in parallel to the capital it represents (which is amplified by speculation), but independent, which means the actual capital is then expended and generates profit separately. The value is still being generated and consumed in the commodity, the share just allows for capitalists to finance the production of said commodities in a more convenient way, and the price of share tracks the overall growth of the economy on average so no additional value is ever being created.