Amazon.com launched a cheaper, wireless-only Kindle Wednesday, betting that the $139 price will turn its latest electronic reader into a mass-appeal device as Apple Inc’s iPad gains ground.

The world’s largest online retailer and leading e-reader seller also revealed its third generation Kindle, some 21 percent smaller and 15 percent lighter than the previous version, but still priced at $189.

Amazon does not give sales figures for the Kindle, but said last week that its growth rate tripled after it cut its price on the device from $259 and said e-books were outselling hardcover books. Apple has said it sold more than 3 million iPads, starting at $499, since the product was introduced in April. Get the full story »