Spirit Airlines acquisition has taken an unexpected hostile turn

In February, Frontier Airlines announced it was buying fellow ultra-low-cost carrier Spirit Airlines in a $2.9 billion cash-and-stock deal. But Frontier’s hopes of a straightforward acquisition were dashed a few months later, when JetBlue made an unsolicited $3.6 billion cash offer to buy Spirit if it withdrew from the Frontier merger.

But Spirit is holding onto the Frontier deal.

Now JetBlue goes directly to Spirit shareholders, CNN reports, trying to convince them to vote against the Frontier deal, as it presents an all-cash offer of $30 a share. JetBlue said in a statement Monday it was offering a “60% premium on the value of the Frontier transaction,” adding that it is willing to negotiate if Spirit discloses more information about its company.

Related: Flight Prices Hit Record Highs, Raising Red Flags for Summer Travel

Frontier’s January offering valued each Spirit share at $25.83.

Spirit cites anti-monopoly regulation as a major barrier to closing a deal with JetBlue. Ghost Rejected JetBlue’s cash offer of $33 per share on May 2, stating that in light of “significant completion risk, we believe JetBlue’s economic offering is an illusion”.

If the Frontier-Spirit merger were to take place, the new airline would surpass JetBlue in size and customer base, becoming the fifth largest airline in the country.

JetBlue Airways Corporation is down nearly 24% month over month, while Frontier Communications Parent Inc is down nearly 20% over the same period.

Related: Passengers Outraged After Southwest Airlines Leaves Thousands Of Stranded People