The market's expected move for TCS's results

On 8 Oct 2026 (bhavcopy) the TCS 27 Oct ATM straddle was ₹118.50 with parity forward ₹2,076.99 and 19 calendar days to expiry. ATM IVs were 31.41% (27 Oct, 19 days) and 29.39% (23 Nov, 46 days, from settlement prices). (a) Invert the straddle with the 0.8 rule (M09A (9A.8), $r$ ignored) to get an implied volatility. (b) Use M09A (9A.13) to extract the event standard deviation $\sqrt e$ and the ordinary volatility $\sigma_d$. (c) Compute the event-day standard deviation $\sqrt{e + \sigma_d^2/365}$ and the expected absolute event-day move, as percentages. (d) The realised move to the 9 Oct close was +3.86%. How many event-day standard deviations is that? Why is the 23 Nov input the weakest part of the calculation?