Editors' pick: Originally published May 25.

Delta's (DAL) - Get Delta Air Lines, Inc. Report decision to order 75 Bombardier CS100 jets may be the harbinger of dramatic change in an aircraft manufacturing industry that has long been the purview of two companies, Boeing (BA) - Get Boeing Company Report and Airbus, according to a new report by a Moody's aerospace analyst.

"The beginning of the end of the long-running Boeing/Airbus duopoly is upon us," wrote Moody's analyst Russell Solomon in a report issued Tuesday and titled "The Gloves Come Off as Boeing and Airbus Fight More Than Just Each Other for Share."

On April 25, Delta announced its order for 75 CS100s, the largest order in the history of Bombardier's commercial aircraft business segment. "Bombardier has joined the ranks of the two big OEMs, and Embraer, in the 100-plus seat narrowbody market," Solomon wrote. "A steep pricing discount, earlier availability and perhaps the most technically proficient model available in its class likely landed the must-have order for Bombardier.

"For about the past two decades, the market for large commercial airplanes (100 seats or more) has essentially been a duopoly comprised of the Boeing Company (A2 stable) and Airbus Group SE (A2 stable)," he wrote. "Bombardier Inc. (B2 negative) let everyone {see} just how serious it is about joining the two leading OEMs and Embraer S.A. (Ba1 negative) in the big pool, even if only in the shallow end for now.

"While they will no longer have the market to themselves, we expect Boeing and Airbus to retain the lion's share of the large commercial airframe market, with emerging competitors garnering only a relatively modest low single-digit share," wrote Solomon, who noted that pricing pressure will continue.

Boeing shares closed Tuesday at $127.50 and have declined 12% year to date. That is the second worst performance among the Dow 30 stocks: Year to date, Goldman Sachs is down 13%, while the Dow Jones Industrial Average has risen 2%. Airbus ADRs closed Tuesday at $15.60 and are down 7% year to date.

Still, Boeing "remains one of the highest rated companies we rate (certainly in the global aerospace & defense industry sector), and operates in one of the few industry sectors for which we maintain a positive outlook/bias," Solomon said in an interview.

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"Part of the underlying rationale for high ratings is the implicit ability to overcome challenges," he said. "Right now, Boeing's got more challenges than Airbus, speaking to this specific context only --c ivil aerospace, narrowbodies -- but the 100-year track record is nothing to sneeze at."

In his report, Solomon said the Boeing/Airbus rivalry is growing more intense as Airbus wins more narrowbody orders. Airbus has the advantage of a one-year head start in production of its re-engined narrowbody, the A320 neo, and it is ramping up narrowbody production rates faster than Boeing.

However, Solomon said, "Airbus will continue playing catch-up in the widebody market, ramping production rates for its still young A350 program to match Boeing's earlier launched 787 program."

Meanwhile, the aircraft market has come to favor buyers over sellers, with oil prices down and the number of new orders slowing, forcing both Airbus and Boeing to accept lower profitability in order to protect market share.

Not only did the CS100 sell at a discount, but also United is believed to have received a steep discount when it ordered 25 current generation Boeing 737-700s in February. Bombardier competed for the order up until the final week.

It's unclear whether American (AAL) - Get American Airlines Group, Inc. Report can take advantage of falling prices for aircraft. In 2011, American placed the largest aircraft order ever for 460 aircraft from Boeing and Airbus. "Combined with US Airways' pre-merger order book, American really has no need to place additional orders for mainline aircraft," Solomon said in the interview. "Although as one of the biggest customers of Boeing and Airbus, they have pricing power, it is not clear to us that they have flexibility to modify/re-price existing contracts."

Looking ahead, Solomon wrote, by the end of the decade Boeing and Airbus combined will produce about 120 single-aisle airplanes every month. Competitors' combined annual production will be only slightly higher, he said, but competitors will continue to nibble around the edges of the order books.

Moreover, Solomon said, Bombardier is likely to produce a larger variant, with 160 to 180 seats, by stretching its forthcoming CS 300 aircraft with 130 to 160 seats. "Such an airframe would fall much more squarely in the middle of the Boeing/Airbus fairway for single-aisle jets, presenting an even bigger challenge to their duopoly standing," he wrote. "The ensuing pricing environment would then heat up even more."

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.