Dis-synergy
M&A / Merger ModelA permanent cost a transaction creates rather than removes, most often the extra cost of running a carved out business alone.
Also written: dissynergy, dis-synergies, negative synergy
Synergy analysis usually runs in one direction, listing what a combination takes out. A dis-synergy runs the other way: a cost that exists only because the transaction happened. In a carve out the largest one is structural, since the business loses the parent's purchasing power and has to buy the same services at its own smaller scale.
It is the exact inverse of an economy of scale. Where a merger takes two overheads and makes one, a separation takes one overhead and makes two, and the second is bought without the volume that made the first cheap.
Dis-synergies are not confined to separations. A combination can create them too: customers who will not buy from a single supplier after two suppliers become one, staff who leave, a regulatory remedy that forces the disposal of a profitable site, or the cost of running two enterprise systems until one is retired.
Treat them exactly as you would treat synergies, and with the same discipline: state whether they are permanent or temporary, tax them if they are pre tax, and capitalise the permanent ones. A candidate who volunteers the dis-synergy alongside the synergy sounds like someone who has argued about a model rather than read about one.
Worked example
A division is charged 8 of group overhead and will spend 14 standing alone. Illustrative figures.
The 6 difference is a permanent dis-synergy. On EBITDA presented at 50, the real standalone figure is 44.
At a 9.0 times multiple that 6 is worth 54 of enterprise value, which is why the adjustment is a negotiation rather than a footnote.