14.17 Short selling and securities lending (SLB)

Motivation

A short sale profits from a price fall: sell shares you do not own, buy them back later. In India the cash market allows this only within a day unless you have borrowed the shares through the exchange's lending scheme. Understanding why tells you which instrument to use for a bearish view and what it costs.

14.17.1The regulatory frame#

SEBI's short-selling framework dates from a December 2007 circular, effective 2008, was restated in the master circular for stock exchanges and clearing corporations (October 2023), and was updated by circular SEBI/HO/MRD/MRD-PoD-3/P/CIR/2024/1 of 5 Jan 2024 (secondary summaries: TaxGuru, Business Standard via search, January 2024). Its main provisions:

All classes of investors, retail and institutional, may sell short.
Naked short selling is not permitted. Every seller must deliver the securities at settlement. A short sale must therefore be covered by a purchase the same day or by borrowed securities.
Institutional investors must disclose upfront, when placing the order, that a sale is a short sale. Retail investors must make the disclosure by the end of the trading day. Exchanges consolidate and publish short-selling data weekly. (The 2007 framework also barred institutional investors from intraday square-off; that restriction is reported in secondary summaries and was not checked against the current text.)

Intraday shorting in the cash market A retail short sale in an intraday product (MIS) is squared off by the broker before the close. If it is not covered, the seller has a short delivery at T+1 settlement: the exchange runs an auction to buy the shares, and if the auction fails the position is closed out at a price set by the exchange's close-out rules, which can be far above the market. The cost is open-ended. Do not carry an uncovered cash short overnight by accident.

14.17.2Securities Lending and Borrowing (SLB)#

Mechanics (NSE pages as summarised by search, and broker FAQs; secondary)

An exchange-traded, screen-based market run with the clearing corporation as central counterparty. Lenders offer shares, borrowers bid; the lending fee is the price, quoted in rupees per share for the contract's tenure, and trades match on price–time priority.
Tenure from 1 month to a maximum of 12 months (NSE SLBS features page). NSE Clearing introduced shorter-tenure contracts with a T+3 reverse leg from 17 Aug 2026 for securities eligible in equity derivatives (secondary news report, Aug 2026; not checked against the NSE circular, so verify with the exchange).
Eligible securities: mainly those in the F&O segment, plus some ETFs; the list is published by the clearing corporation.
Borrower margins: the lending price (the value of the borrowed shares) collected in cash or cash equivalents, plus margins of VaR/ELM type and daily mark-to-market (NSE SLBS margin page summary; Business Standard on the 2013 revised scheme). Early recall (by the lender) and early repayment (by the borrower) exist for eligible securities through the platform.
Corporate actions during the loan are compensated to the lender through the clearing corporation (standard SLB practice; the exact NSE procedure was not verified here).

A covered overnight short Borrow $n$ shares through SLB for one month at fee $f$ per share, sell them in the cash market, buy them back before the reverse leg, and return them. The P&L per share, ignoring interest on margin, is

S_0 - S_T - f - \text{STT and charges on the sale and the purchase}.

As of 6 Nov 2026 (NSE circular NSE/FATAX/73524; M01 · 1.7), delivery STT is 0.1% on both buy and sell, so the round trip costs about 0.2% of value in STT alone.

14.17.3SLB versus stock futures: the implied borrow cost#

The other way to be short overnight is to sell a single-stock future (physically settled at expiry; M07 · 7.4). The comparison is a cost-of-carry calculation.

Proposition 14.24implied borrow fee

Let a stock with continuous dividend yield $q$ trade at $S$ , its future for maturity $T$ at $F$ , the risk-free rate be $r$ , and let short sellers who can earn $r$ on sale proceeds pay a continuous borrow fee $b$ . Then absence of arbitrage requires $F \ge Se^{(r - q - b)T}$ , and the implied borrow fee

b_{\text{imp}} = r - q - \frac{1}{T}\ln\frac FS \tag{14.17}

is the fee at which shorting through SLB and shorting through the future cost the same.

Proof

Model the dividend and the fee as continuous yields owed in shares: a borrower of one share at time 0 owes $e^{(q+b)T}$ shares at $T$ (the standard continuous-yield bookkeeping of M07 · 7.1). Run the reverse cash-and-carry scaled so that exactly one share is owed at $T$ : borrow $e^{-(q+b)T}$ shares, sell them for $Se^{-(q+b)T}$ , invest the proceeds at $r$ , and buy one future at $F$ . At $T$ take delivery of one share through the future, paying $F$ , and return it to the lender. The cash account holds $Se^{(r-q-b)T}$ , so the payoff is $Se^{(r-q-b)T} - F$ . It is riskless and the strategy cost nothing at inception, so absence of arbitrage requires $Se^{(r-q-b)T} - F \le 0$ . The fee at which the payoff is exactly zero solves $\ln(F/S) = (r - q - b)T$ , which is (14.17). ∎ If the SLB fee is below $b_{\text{imp}}$ , SLB is the cheaper short for someone who earns $r$ on the proceeds; if above, sell the future. A future trading well below its carry value ( $b_{\text{imp}}$ large) is the market telling you the stock is expensive to borrow: shorts are crowded, and squeezes are possible.

The retail case In practice the sale proceeds of an SLB short are blocked against the borrower's margin and earn nothing for most retail accounts. Then compare directly: SLB delivers $S_0 - f$ less STT on both legs; the future delivers $F$ less STT on the sale of the future (0.05% from 1 Apr 2026: Finance Act, 2026, as set out in NSE circular NSE/FATAX/73524 of 31 Mar 2026). In Problem 14.26, with $S = 1{,}000$ , a one-month future at 1,002 and an SLB fee of ₹3, the future is ₹6.50 per share cheaper.

Other bearish instruments Buying a put (M08) caps the loss at the premium and needs no borrow; selling a call spread or futures are the other choices. For an index view, Nifty futures or options are the natural short; single-stock shorts carry gap risk on results and the risk that the stock is locked at its upper price band when you need to buy back (M01 · 1.5).

Practitioner notes

A short has an unbounded loss and a bounded gain. Size it on a stop and on a gap scenario (14.15), not on the stop alone.
A short via SLB can be recalled or become expensive to roll; a short via futures has to be rolled each month at the then-prevailing basis.
Short interest is information. Rising SLB fees and futures at a discount to fair value mean other shorts are paying up; your expected return net of the borrow cost is lower than it looks, and squeeze risk is higher.