Amazon.com Inc., of course, shares some of the blame for Toys ‘R’ Us Inc.’s bankruptcy filing. However, experts say there are a number of reasons why the toy retailer filed chapter 11, some that go back for years indicating the company was in trouble for quite some time.

“Certain larger retailers that filed for bankruptcy had burdensome levels of debt resulting from their private equity owners’ uses of financing in acquiring the companies,” tax and advisory firm BDO wrote in a September report.

In addition, UBS analysts led by Arpine Kocharyan wrote in a Monday note that a “chapter 11 filing heading into Q4 may be indicative of a subdued holiday outlook by Toys ‘R’ Us.”

The toy retailer’s bankruptcy filing was triggered by stricter terms from vendors and suppliers ahead of the holidays, The Wall Street Journal reports. The filing was expected, and comes as all of retail is undergoing a shift to e-commerce and heightened competition from a variety of sources. Toys ‘R’ Us operates about 1,600 stores around the world, and said business would proceed as usual for customers, though some bankruptcy experts warn there could be noticeable changes, like difficulty finding popular toys.

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Toys ‘R’ Us plans to use the bankruptcy to restructure $5 billion in debt and create “a sustainable capital structure.” The debt, $444 million of which was due next year, stems largely from a $6.6 billion leveraged buyout, led by Bain Capital, KKR & Co. KKR, -1.01% and Vornado Realty Trust VNO, -5.19% in 2005.

In the first six months of 2017, more than 20 retailers filed for bankruptcy with thousands of stores closing.

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“Fixed interest and lease payments proved too onerous for these leveraged retailers as sales and margins deteriorated. Other failing retailers will likely opt for leveraged buyouts in the second half of 2017 as private equity-backed retailers struggle to restructure their high levels of debt,” BDO wrote.

Toys ‘R’ Us says it has received a $3 billion debtor-in-possession loan that allows it to keep operating.

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On Tuesday, UBS reiterated the impact that holiday season dependency has had on the toy retailer.

“Increasing reliance on holiday sales, with profitability tied to successful inventory management, shifting of shopping patterns closer to holiday season and pricing pressures of more diversified discount retailers have made it particularly challenging for traditional specialized retail outlets to do well over time,” the Tuesday UBS note said.

UBS says other retailer restructurings or bankruptcies, like that from Sears Holding Corp. US:SHLD, FAO Schwarz and KB Toys, haven’t had an impact on toy sector growth since sales have moved online. However, Toys ‘R’ Us was slow to go digital.

“The fact that Toys ‘R’ Us ceded control of its own online offering to Amazon during a period where e-commerce began to really take off meant that the retailer was always playing catch up with its online competitors,” said Jon Copestake, chief retail and consumer goods analyst at the Economist Intelligence Unit.

“Alarm bells will have been ringing for some time but it took until May this year for an online store revamp to take effect and it is difficult to see how Toys ‘R’ Us could address the structural challenges it faced without reducing its store footprint and significantly changing its proposition,” Copestake said.

Other experts note changes in the “economics of toy store retailing” despite far less change in price. According to Neil Saunders, managing director of GlobalData Retail, Amazon.com Inc. AMZN, -1.78% has, like in many other areas, hurt Toys ‘R’ Us. GlobalData estimates that 13.7% of toy sales in 2016 were made online, up from 6.5% five years ago. And the low prices and convenience from retailers like Wal-Mart Stores Inc. WMT, -1.02% hasn’t helped.

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“[T]he extra competition has meant that the price of toys—many of which are branded and therefore easily comparable between stores—has risen little over the past five or so years, exerting significant pressure on margins,” Saunders said. “Second, specialists have gradually seen their share of the toy market eroded.”

There are also forces at work from outside the toy sector.

“[T]he impact of competition from outside the sector has been equally, if not more, punishing with retailers like Apple AAPL, -3.17% and its App Store, taking more of kids spend than ever before,” Saunders said.

He emphasizes that the interest in electronics isn’t new, but it was once complementary to the toy store buy rather than a replacement for it, like a smartphone or tablet. Moreover, those complementary purchases were made at toy stores rather than elsewhere.

With its traditional retail channels threatened, Jim Fosina, chief executive of Fosina Marketing Group, suggests toy manufacturers like Mattel Inc. MAT, -1.68% and Hasbro Inc. HAS, -0.62% follow the lead of companies like Nike Inc. NKE, -1.46% and turn to direct-to-consumer channels.

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“Can the toy manufacturers reach consumers directly before margins are cut so deep that it’s going to be problematic for them?” Fosina asks. “They used to be able to maintain customer relationships through retail. They have lost as retail has lost its footing with consumers’ new buying patterns and desires.”

Mattel’s stock has tumbled 24.6% over the past three months through early Wednesday, while Hasbro shares have shed 15% and the S&P 500 index SPX, -1.11% has tacked on 3%.

If Hasbro and Mattel, which have strong recognition through their names and the names of their brands, could successfully sell their product through direct-to-consumer methods, Fosina says, “they might have some of the strongest opportunities to excel.”