Cross-Border M&A: 2026 Hart-Scott-Rodino Filing Thresholds, Second Request Costs & Antitrust Review

## Antitrust Risk Architecture in Corporate Consolidation

Navigating premerger notification under the Hart-Scott-Rodino (HSR) Antitrust Improvements Act requires precise evaluation of jurisdictional thresholds and market concentration indices. The Federal Trade Commission (FTC) and Department of Justice (DOJ) scrutinize both horizontal competitive overlap and vertical integration efficiencies.

### 1. HSR Tiered Filing Fee Structure (2026 Adjusted Schedules)

Filing fee tiers are determined by the aggregate value of voting securities, non-corporate interests, and assets held as a result of the transaction:

| Transaction Value Tier | Statutory HSR Filing Fee | Typical Waiting Period | Second Request Likelihood |
|:-----------------------|:------------------------:|:----------------------:|:-------------------------:|
| $119.5M to $536.5M | $30,000 | 30 Calendar Days | 1.8% |
| $536.5M to $1.073B | $105,000 | 30 Calendar Days | 4.2% |
| $1.073B to $2.146B | $260,000 | 30 Calendar Days | 11.5% |
| $2.146B to $5.365B | $415,000 | 30 Calendar Days | 28.0% |
| Greater than $5.365B | $2,335,000 | 30 Calendar Days | 62.4% |

### 2. The Herfindahl-Hirschman Index (HHI) Test

Regulatory review centers on changes in market concentration:

$$\text{HHI} = \sum_{i=1}^{N} s_i^2$$

Markets with a post-merger HHI exceeding 1,800 points and an increase of more than 100 points are presumed likely to enhance market power under the 2023 FTC/DOJ Merger Guidelines.