# ATM volatility and flat volatility

Why do the implied volatility curve and the flat curve cross over the ATM volatility (at 100%) ?

Tx

• This question has no context. It is as if I showed you an apple and an orange and asked: Why ? – Quantuple May 4 '16 at 13:07
• I've edited : don't hesitate if you need more context – glork May 4 '16 at 13:48