Herfindahl- Hirschman Index- HHI


My Wiley study notes say the following:

If the HHI of an industry is 1000-1800, it is moderately concentrated, and an increase of the HHI above 100 (as a result of a merger) is likely to be challenged. Otherwise, if the increase is below 100, it will likely not be challenged.

My question is: what if the HHI is something close, like 1780? Even a 20 point increase will then push it into the 1800+ category, which is categorized as highly concentrated.

Even though the increase is just 20 points, will the merger be challenged on the grounds of it shifting the industry into high-concentration territory?

Thank you guys.

No it won’t as long as your within the rules of the game. However, the regulations will tighten once the industry becomes heavily concentrated as a 50 point increase in mkt share will be called out.