I think it’s simpler than that.
How many contracts are needed to replicate 15m earning 2% over 6 months? First, work out the future value of 15m in 6 months = 15.15m
Then divide that by the price of a contract to get the # of contracts = 15.15m / 37k = 409. Done!
More complex bit:
Now, if you want prove that 409 contracts is synthetically equivalent to investing 15m in cash equivs for 6 months, you’d need to know what the market ending value is. Let’s pretend it’s 3500 (3700 is the beginning value).
409 * 37000 is 15.133m. Today that’s worth 14.984m using the 2% rf rate. Thus, if you’d invest that in cash for 6 months at 2%, you’d have 15.133m
So, we bought 409 contracts, and the multiplier was 10 (think of this number as # of shares per contract) = 4090 shares, this represents the # of terminal shares at the end of 6 months.
The market went down from 3700, to 3500. We sold contracts, so we made a gain of (3700 - 3500)(4090) = 818k
The ending shares are worth (4090)(3500) = 14.315m
Total = 14.315m + 818k = 15.133m
That’s equal to investing in cash!
The only time you’d need the dividend yield, is if you were asked what the equivalent number of shares required today you’d need to replicate the above. You worked out your terminal number of shares as 4090, so bring that back to today using the dividend yield of 3% over 6 months = 4030. If you bought 4030 shares today, you’ll earn 3% dividend yield, resulting in 4090 in 6 months.