How do you treat corporate overhead in an SOTP?

costs not allocated to segments (holding functions, corporate headquarters, treasury, corporate communications). Treatment:

• Pro-rata allocation: overhead × segment revenue / group revenue → reduces each segment's EBITDA.
• Separate deduction: overhead as a 'negative value' at the end of the SOTP — capitalized at a group-wide multiple (e.g. −$200m for $30m of overhead at a 6.7x multiple). IB standard: method (2), because overhead cannot be mapped one-to-one to segments.