New Delhi, June 24 -- Beyond headline indices and P/E multiples, one under-the-radar tool can help investors assess when equities offer more bang for the buck than bonds-and vice versa. It's called the earnings yield to bond yield ratio, and it might just give you a smarter lens into market valuation.

Think of earnings yield as the return you'd get for every rupee you invest in equities. It's simply the inverse of the price-to-earnings (P/E) ratio. For example, say the Nifty50 index is at 25,000 and the combined earnings per share (EPS) of its constituent companies is Rs.1,120. Dividing 25,000 by 1,120 gives a P/E ratio of 22.32. Inverting this gives an earnings yield of 4.48%. That means, based on trailing twelve-month (TTM) earnings, y...