On Monday, after market hours, India’s biggest domestic airline, IndiGo, operated by Interglobe Aviation, announced an all-round improvement in sales and profits. The same evening,the airline’s top management—president and whole-time director Aditya Ghosh and chief financial officer Rohit Philip—told investors at an earnings conference call that IndiGo would move into owning aircraft. That’s a dramatic shift from Indigo’s now-famous ‘sale and lease-back’ model.

The result?Despite posting a 37% increase in net profit for the first quarter over the corresponding year ago period, the carrier’s shares fell 0.1% on Tuesday to Rs 1,288.95 on the BSE. The fall continued on Wednesday—it closed 0.73% lower.

To those following the airline, this news shouldn’t have come as a shock. A month ago, the airline’s promoter Rakesh Gangwal had hinted at such a change. During a conference call in early July, Gangwal said that Indigo needed to be asset-light in its early days when the airline was in startup mode. “But once an airline becomes very large like us, you need to start looking at ways to figure out if there are other optimal structures to look at. Companies like Southwest Airlines, Ryanair are not asset-light—they own a large number of airplanes. So, we are looking at that model, trying to understand how and when, and what we should do,” he said. This went under the radar as the spotlight then was on IndiGo considering an offer for Air India.

Though IndiGo has always downplayed the importance of its sale and lease-back model, competitors claimed it was the secret sauce for the Gurugram-based low-cost carrier’s consistent profitability. Typically, the fleet mix of Indian airlines has had a larger share of owned aircraft. But with IndiGo posting profits year after year, other domestic airlineshave increased the use of the sale and lease-back model to acquire aircraft and reduce the stress on their balance sheets.

As on July 31, 2017, IndiGo had a fleet of 136 Airbus A320s of which 87% are on operating lease while only 13% are owned or on financial lease. And as on June 30, IndiGo had a total debt of Rs 2,524.10 crore while it had total cash reserves of Rs 10,184.7 crore of which Rs 5,188.8 crore was free cash and Rs 4,995.9 was restricted cash. Switching to owning aircraft outright or through financial lease will change the cash rich balance sheet for IndiGo. Sample this: According to data from Airbus, an A320neo aircraft, which IndiGo uses, costs $108.4 million (Rs 691.92 crore) at list price.

IndiGo’s image as a conservative spender is slowly changing. The airline was among the frontrunners to buy stake in the debt-laden, Air India. However, when its stock price took a beating after it announced its intentions to buy the public-sector airline, it withdrew from the race. And now with IndiGo wanting to buy its own aircraft, analysts are feeling nervous.

In a research note, Parita Ashar, Ambit Capital’s analyst wrote: “We see rising risks from entry into newer operations (regional routes/acquisition of Air India’s international operations) and move to asset-heavy business model.”

Rakesh Jhunjhunwala, one of the biggest investors in the country, was on Monday evening’s conference call, and he, too, had his concerns. He sought more clarity on the management’s new strategy towards aircraft acquisition. However, the management had little to offer apart from stating that the change will be gradual.

However, there are those like ICICI Securities’ Ansuman Deb who see positives in the change of strategy. In a note to investors on Tuesday, Deb wrote, “Continuing with an active aircraft management policy, IndiGo is now gradually shifting to owning airplanes. We find merit in this policy, considering that over the long run, owning an aircraft will be cheaper than leasing and IndiGo can afford to aim at such optimisation considering its balance sheet strength.”

So, the message coming from the management and promoters is clear: IndiGo is no longer a startup and the asset-light balance sheet that has defined its existence is going to change. But one this is for sure, analysts will keep a hawk eye on how this strategy will affect its attractive balance sheet.