On Wednesday, Ken Chenault said that high-income earners were pulling back on their spending -- in contrast to previous periods of economic downturn. He should know: As the CEO of upscale payment card issuer American Express (NYSE:AXP), he's got a prime perch from which to observe the spending habits of mass affluent consumers.

That spells bad news for AmEx and its competitors Visa (NYSE:V) and MasterCard (NYSE:MA), but it also highlights two other sectors that could be particularly vulnerable to this downturn: luxury brands such as Tiffany (NYSE:TIF) and Ralph Lauren and high-end retailers like Nordstrom and Saks.

Last month, at the 2008 Luxury Briefing Conference, Claire Kent -- a former Head of Luxury Research at Morgan Stanley -- said the "bursting of the 'It' bag bubble" was imminent. She also singled out brands whose strategy relies on customers "trading up" as being particularly vulnerable. That's two strikes against handbag and accessories maker Coach (NYSE:COH), for example.

Bad for chic, good for cheap
For investors, it's not all bad news, though. When consumers are forced to trade down instead of up, that can create opportunity for a different set of companies. Target's (NYSE:TGT) "cheap and chic" positioning -- not to mention Wal-Mart's (NYSE:WMT) "just plain cheap" approach to retail -- look a lot better suited to this environment than Coach's "masstige" strategy.

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