The days of Spirit and its famous flying yellow highlighters might be coming to an end. The company announced today that it would merge with Frontier in an effort to create a low-cost budget giant with real ramifications for the broader airline industry.

The cash-and-stock deal will value the two companies at $6.6 billion, including liabilities and debt. 

The company’s press release touched on the new carrier’s goals of delivering more than $1 billion in annual savings and expanding frequent flyer and membership offerings. However, what the release failed to highlight is just how giant this new budget airline would be.

The transaction will see Frontier own a small majority (51.5%) in the business, while Spirit equity holders will make up 48.5% of the shareholders in the completed transaction.

Ultimately, we’re not sure if this will end up being an Avis-Budget sort of deal (where Spirit-Frontier operate as two separate airlines, but share balance sheets and synergies) or if this duo will end up like past carrier mergers (two carriers merge under one name.)

The deal sent shares of Spirit flying by more than 17% today. While shares of Frontier only rose by 3%.

These two airlines have much greater competitive potential together.