Exceljet

Quick, clean, and to the point

Excel DISC Function

Excel DISC function
Summary 

The Excel DISC function returns the discount rate for a security.

Purpose 
Get discount rate for a security
Return value 
Discount rate as percentage
Syntax 
=DISC (settlement, maturity, pr, redemption, [basis])
Arguments 
  • settlement - Settlement date of the security.
  • maturity - Maturity date of the security.
  • pr - Security price per $100 face value.
  • redemption - Security redemption value per $100 face value.
  • basis - [optional] Day count basis (see below, default =0).
Usage notes 

The Excel DISC function returns the discount rate for a security. A discounted security does not pay periodic interest, but has a specified redemption value at maturity. The return on a discounted security is the difference between the price and redemption value.

Discount rate is based on the concept of the time value of money. The discount rate is the interest used to convert between future value and present value. A future value can be "discounted" by a given interest rate to determine the present value.

Example

In the example shown, we want find the discount rate for a bond with a price of $89.50 and a redemption value of $100. The settlement date is 6-Jul-2017 and the maturity date is 15-Jan-2020. The day count basis is US (NASD) 30/360. The formula in F5 is:

=DISC(C7,C8,C5,C9,C10)

With these inputs, the DISC function returns 4.16%, with percentage number format applied.

Entering dates

In Excel, dates are serial numbers. Generally, the best way to enter valid dates is to use cell references, as shown in the example. To enter valid dates directly inside a function, you can use the DATE function. To illustrate, the formula below has all values hardcoded, and the DATE function is used to supply each of the two required dates:

=DISC(DATE(2017,7,6),DATE(2020,1,15),89.5,100,0)

Basis

The basis argument controls how days are counted. The DISC function allows 5 options (0-4) and defaults to zero, which specifies US 30/360 basis. This article on wikipedia provides a detailed explanation of available conventions.

Basis Day count
0 or omitted US (NASD) 30/360
1 Actual/actual
2 Actual/360
3 Actual/365
4 European 30/360

Notes

  • In Excel, dates are serial numbers
  • All dates, and basis, are truncated to integers.
  • If dates are invalid (i.e. not actually dates) DISC returns #VALUE!
  • DISC returns #NUM when:
    • settlement >= maturity
    • pr <= 0 or redemption <= 0
    • Basis is out-of-range

Excel Formula Training

Formulas are the key to getting things done in Excel. In this accelerated training, you'll learn how to use formulas to manipulate text, work with dates and times, lookup values with VLOOKUP and INDEX & MATCH, count and sum with criteria, dynamically rank values, and create dynamic ranges. You'll also learn how to troubleshoot, trace errors, and fix problems. Instant access. See details here.