July 1 marks a key moment for U.S. liquids pipelines, as many regulated by the Federal Energy Regulatory Commission (FERC) may see rate increases tied to the Oil Pipeline Index. This year’s adjustment, capped at 1.43%, reflects a formula using the Producer Price Index for Finished Goods (PPI-FG) with a 0.55% reduction. The change follows a five-year review of the index, which sets the ceiling for annual rate adjustments for pipelines transporting oil, natural gas liquids, and refined products.
Understanding the Oil Pipeline Index
The Oil Pipeline Index, managed by FERC, ensures that interstate pipeline rates remain just and reasonable. Established in the 1990s, the index was designed to streamline cost-of-service filings and reduce litigation. In April 2026, FERC finalized a new five-year framework, setting the index at PPI-FG minus 0.55%. This adjustment represents an improvement over an earlier proposal that would have subtracted 1.42% from PPI-FG, offering pipelines a slightly higher floor for rate changes.
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The index is reviewed every five years to align with industry cost trends and maintain regulatory balance. For 2026, the PPI-FG rose 1.979% in 2025, leading to the 1.429% rate increase. This marks the smallest adjustment in the past five years, but rising inflation could push future increases higher, particularly in 2027.
2026 Rate Adjustment and Historical Context
The 2026 rate adjustment is part of a broader trend. In 2023, the index saw a record 14.3% increase, driven by soaring inflation in 2022. Adjustments in 2024 and 2025 were more modest, around 2% annually. The 1.43% cap for 2026 reflects a slowing pace of inflation but highlights the index’s sensitivity to economic shifts.
While the index directly affects 195 FERC-regulated pipelines, its influence extends beyond them. Many midstream assets, including intrastate pipelines, terminals, and storage facilities, use the index in contracts to align rates with inflation. Some pipelines, like those operated by ONEOK, rely on market-based rates instead of the FERC index, with 70% of their refined product and crude volumes using negotiated pricing.
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Regardless of the rate-setting method, long-term midstream contracts often include inflation adjustments. Enterprise Products Partners, for example, notes that about 90% of its long-term agreements have escalation clauses to protect cash flows. This structural feature, combined with real asset exposure, has historically helped midstream companies and master limited partnerships (MLPs) perform better during inflationary periods.
Real assets may be the missing piece in portfolios. As 2026 EBITDA guidance reinforces midstream stability, the combination of inflation protection and tangible infrastructure positions the sector to manage economic fluctuations. This dynamic could become even more pronounced as inflation pressures evolve, offering investors a potential hedge against broader market volatility.
