Over the last half-century, economic growth stagnated but stock-market wealth boomed. I present evidence that declining innovation productivity reconciles these trends. At the macro level, I document that R&D spending has fallen relative to value, while M&A spending has doubled relative to R&D. At the micro level, most of the increase in aggregate valuation ratios is explained by a reallocation of sales shares toward high-valuation firms. Using a Schumpeterian model of growth and asset prices, I find that declining innovation productivity explains these facts. When innovation productivity falls, R&D falls and M&A rises. This concentrates production into the hands of the most efficient (high-valuation) incumbents, causing aggregate value to boom. Quantitatively, this explains most of the decline in growth and the rise in valuations. It also helps explain other salient trends, including declining firm entry, rising concentration, and falling interest rates. While stock-market wealth boomed, the present value of consumption (consumer welfare) stagnated with output.