(CNN) - Monday is Amazon Prime Day. So is Tuesday.
The fifth annual Prime Day will run a full two days this year. Amazon says it will launch new deals as frequently as every five minutes.
The company's global sales for the 48-hour marathon are estimated to hit $5.8 billion.
Amazon is facing increased competition on its biggest yearly sale. Rival retailers including Walmart, Best Buy, Target and eBay have had years of practice perfecting their Prime Day counterstrategies, and they're rolling out discounts of their own.
More than 250 retailers are planning deals, aiming to benefit from a halo effect of Prime Day.