# Curve Euribor - Euribor 3M

I'm setting up some Euribor 6M and Euribor 3M curves. So far i have all the data and quotes i need, but i'm having trouble defining the firsts points of the curve. I'm currently using 6M Euribor and 3M Euribor OIS as the first point.

My question is, how correct is it if i use O/N Euribor or 1M Euribor on both curves, knowing that there's a basis between the indexes.

As an example, for the 6M Euribor these are my two options:

• Euribor O/N, Euribor 1M, Euribor 6M, FRAs, Swap Rates.
• Euribor 6M, FRAs, Swap Rates.

Both options seem correct, but i don't know what is the market convention over this.

Thanks for the help.

It is incorrect to use 1m euribor or O/N euribor in a 6m Euribor forward curve. You should only use instruments based on 6M euribor, such as 1x7 FRA, 6x12 FRA or swaps v 6m Euribor, as you have done in your second example. The actual 6m euribor fixing itself can be thought of as a 0x6 FRA out of spot.

Before the financial crisis basis between different euribor curves didn't really move and wasn't considered an important risk, so it was standard practice to use euribor instruments of any tenor in the same curve. Hence you can find many old textbooks where futures based on 3m Euribor and swaps v on 6m euribor are used in the same curve, which isn't done nowadays.

Incidentally I don't understand the term '3MEuribor OIS' An OIS curve is a separate thing from a euribor Curve. You would build an OIS discounting curve first, then use those discount factors when building your forward curve.

In my experience the first point of a 3M euribor forward curve should be the 3m euribor fixing out of spot, and the first point in a 6m euribor forward curve should be the 6m euribor fixing out of spot.

• Thanks, for the answer, i was thinking the exact same thing. Nov 16, 2014 at 23:40

Once upon a time, there was the One Curve. It was made of various instruments (Depos, Fixings, Futures, Swaps) and represented the One True Discount Rate for any given term. With that curve, and an appropriate interpolation method, it made sense to talk about expensive days, the curve up to 3m, etc.

But that world is long gone. When you create a 3m curve now, you are really trying to calculate expectations of the 3m fixing from your 3m-specific instruments (3m Fixing, FRAs or Futures with adjustment, 3m Swaps), given a known discount curve (built from the instruments specific to the measure, i.e. EONIA for vanilla contracts).

So what does that portion of the curve you are constructing really mean? What is the 1w point on a 3m curve? It doesn't matter. It only matters what the 1w to 1w+3m ratio is, because that's what gives you the expectation of the fixing. Or better yet, dispense with factors and make a fixing expectations curve in rate terms, rather than factors.

• Thanks for the answer Phil, i guess is just as you said. Nov 19, 2014 at 15:35