Amid speculation about the arrival of Apple's next generation mobile phone iPhone 6 or iPhone 5s, Walmart has started offering Apple's iPhone 5 at a $60 discount (from $189 to $129) and iPhone 4S at a $50 discount (from $80 to $39).

The new lower prices were indefinite as of Saturday, June 22.

The offer is only available in stores and not online. In addition, buyers must sign up for a two-year contract with Verizon, Sprint or AT&T as the carrier in order to qualify for the discounted price.

Walmart did not reveal why it made the iPhone price changes but there is speculation that the retail chain may want to dispose of its inventory of the product before the next generation of the iPhone is released, according to MacRumors.com.

Apple Inc. in the past limited how low retailers could drop the price on Apple products. While retailers often offer discounts, a 30 percent price cut in the iPhone 5 retail cost and 70 percent off the price of iPhone 4S is unprecedented, according to Mashable.com.

The price drop puts pressure on other retailers and calls into question how competitors will react and whether or not they will follow suit to match the competition.

Rumors circulated earlier this week that the next Apple iPhone may be called iPhone 5S or iPhone 6 and that it may be released later this summer or in the fall, according to MacWorld.

The next version of the iPhone will reportedly be less costly to make and therefore be available at a lower price point. There is also speculation that it will be available in five different colors and have a larger screen size than the iPhone 5.

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