A stock joins the Satpura 50 and index funds must buy about Rs 900 crore at the close on the effective date, against average daily trading of Rs 150 crore. A facilitation desk can pre-position or offer the funds a guaranteed close. Size the liquidity problem and the desk's risk, and say what happens if the stock falls 4% after inclusion.

Rs 900 crore is 6 days of normal trading demanded in one closing auction, so the funds need a desk that will source the stock in advance and fill them at the close. Buying Rs 300 crore at 20% of volume as the stock runs up 8% gives an average cost near Rs 1,039 and about Rs 11.7 crore of profit if sold at the Rs 1,080 close. Sold into the close, the desk is untouched by a 4% fall the next day; held through it, the desk loses Rs 12.5 crore and ends about Rs 0.8 crore down.

Picture every school in a city telling parents to buy the same uniform from one shop on the same afternoon. The shop sells a hundred a day; it cannot sell six hundred in an hour without either raising its price or having stocked up in advance. Ramtek trades Rs 150 crore a day and the funds need Rs 900 crore at one price on one afternoon: 6 days of normal volume. If the closing auction normally trades about a tenth of daily volume, an assumption to check against the exchange's own data, the event is about 60 times a normal close. Buying patiently at 20% of daily volume instead would take the funds 30 trading days and expose them to tracking error against the index the whole time, which is why they want the close.

The demand figure is itself an estimate that depends on the index method. If the provider revises Ramtek's free-float factor from 0.60 to 0.50 before the effective date, its weight and the funds' demand fall in proportion, to about Rs 750 crore. A desk that sizes its inventory to Rs 900 crore of demand and then sees Rs 750 crore arrive is left with stock no index fund needs. Reading the methodology before sizing is part of the trade, not background.

The desk buys Rs 30 crore a day, 20% of normal volume, for ten days while the stock climbs Rs 8 a day, some of it because buyers like the desk are in the market. It ends with about 28.86 lakh shares at an average of Rs 1,039.49. Sold to the funds at the Rs 1,080 close, that inventory makes about Rs 11.7 crore, a 3.9% edge over cost, and it is the same line that loses if the stock is sold lower. At the funds' close price the order is 83.3 lakh shares; the desk's 28.9 lakh cover about a third, and the other 54.5 lakh must come from sellers in the auction, mostly holders who bought during the run-up and want to sell to the index.

Under a guaranteed close, the funds pay the closing price whatever happens, so the desk's risk is not the close itself; it is any shares it bought earlier at a different price, and any shares it cannot find in the auction. If the auction cannot supply the 54.5 lakh shares, the desk still delivers them and is short the shortfall, buying it back over the following days: a fall then helps it and a further rise hurts. That is why desks charge for a guaranteed close and limit its size to what they believe they can source.

It depends entirely on what the desk holds when the fall comes. Stocks often give back part of an inclusion run-up once the forced buyer has bought, because the demand that lifted the price is gone. A desk that delivered its whole inventory into the close is flat and keeps its Rs 11.7 crore; a desk that held its Rs 300 crore past the event loses Rs 12.5 crore on the fall and finishes about Rs 0.8 crore down, because a 4% fall from Rs 1,080 is below its Rs 1,039 cost. The index funds do not mind the fall in the same way: they hold the stock at its index weight, so the fall moves the index and the fund together and creates no tracking error.

The view a facilitation trader would give is narrow. Pre-position a fraction of the demand, sized to the lower of the demand estimates, about Rs 750 crore if the free float is cut, not the headline Rs 900 crore. Plan to be flat at the close, using the auction to sell inventory rather than as a place to discover how much demand really exists. Charge for a guaranteed close in proportion to the share of the order the desk cannot pre-source. And state the limits: the run-up path, the auction's normal size and the fall afterwards are assumptions in this case, and every one of them should be checked against the stock's own history and previous index events before the desk commits capital.