• We are pleased to announce that the winner of our Feedback Prize Draw for the Winter 2024-25 session and winning £150 of gift vouchers is Zhao Liang Tay. Congratulations to Zhao Liang. If you fancy winning £150 worth of gift vouchers (from a major UK store) for the Summer 2025 exam sitting for just a few minutes of your time throughout the session, please see our website at https://www.acted.co.uk/further-info.html?pat=feedback#feedback-prize for more information on how you can make sure your name is included in the draw at the end of the session.
  • Please be advised that the SP1, SP5 and SP7 X1 deadline is the 14th July and not the 17th June as first stated. Please accept out apologies for any confusion caused.

Vasicek and CIR models

A

Adam

Member
In Section 31.2 of Hull, it says that "The shape of the term structure at time t is independent of r(t), but does depend on t." What does this mean? Could anyone help explain, please?
 
“Shape” is the key word here, as clearly the term structure does depend on r.

The long rate R for both models is a linear function of r. It’s of the form

R=A+B*r

The key point being A and B don’t depend on r.

Hence the overall size of the yields or “level” of the term structure is determined by r, but the general shape of the curve isn’t.
 
Back
Top