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"In light of the continued solid performance of the labor market and our outlook for economic activity and inflation, I believe the case for an increase in the federal funds rate has strengthened in recent months," Federal Reserve Chairwoman Janet Yellen said Friday afternoon in a speech.

Those few words were all it took to abruptly send stocks lower Friday mid-day, despite no set timeline for the potential rate increase.

^SPX Chart

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According to the CME Group's FedWatch tool, the chance of a rate increase at the Fed's Sept. 20-21 meeting is up three percentage points, to 24%. However, in the grand scheme of things, raising interest rates signals a stronger economy and the rebuilding of a tool with which to battle economic downturns in the future -- both good things.

Setting that aside, let's take a look at some of the bigger headlines and movements within the markets this week.

Party like it's 2005

It's been a tough decade for Best Buy Co. (NYSE:BBY), and there are certainly still long-term headwinds facing the company's business model, but that didn't stop the consumer electronics retailer from beating analyst estimates on Tuesday. The earnings beat helped propel the stock more than 17% higher by mid-day Tuesday alone, and it remains 21% higher for the full week.

Starting from the top, Best Buy reported revenue of $8.53 billion during the second quarter, which was $130 million higher than analysts' estimates. Comparable sales managed to climb 0.8% higher, mostly thanks to a 24% rise in domestic online sales. What's more is that Best Buy managed to squeeze out a comparable-store sales gain at the same time NPD reported a 3.2% decline in second-quarter sales for consumer electronics. Looking toward the bottom line, Best Buy's non-GAAP earnings per share checked in at $0.57, up from the prior year's $0.49 level and an impressive $0.14 better than analysts had predicted.

The second quarter was a breath of fresh air for investors hoping Best Buy's initiatives to improve online sales and category management could turn the company's business around. However, domestic gross margin declined 70 basis points, which suggests that, despite beating estimates, the industry's competition is forcing Best Buy to be aggressive with pricing. It was a solid quarter, and hopefully it's a trend that continues for its investors, but this isn't 2005, and we should temper our expectations for Best Buy's turnaround story.

A gift for trailing automakers

One of the hottest topics within the automotive industry over the past couple of years has been the development of autonomous vehicles. There's been a race for many automakers and technology companies to form partnerships, alliances, or to simply navigate their own path toward an autonomous future. Then, something interesting happened this week: Delphi Automotive (NYSE:DLPH) and Mobileye (NYSE:MBLY) announced the two would team up to make a "turnkey" self-driving system.

The turnkey system is aimed to be available for nearly all automakers starting in 2019, and it's a huge deal for some players. No, this isn't a product aimed toward General Motors, which has established through acquisitions, investments in ride-hailing companies, and through its own research how it's going to tackle the future. However, this turnkey product could be the saving grace for automakers like Fiat Chrysler Automobiles, which needs to focus its cash on the current company turnaround before splurging on serious autonomous vehicle programs.

The partnership should hit the ground running, as these two are familiar working with each other. In a press release,Professor Amnon Shashua, Mobileye chairman and chief technology officer, said:

The Mobileye and Delphi relationship started in 2002 with the implementation of what was one of the most advanced active safety systems of the time. Our long history together is key to the success of this ambitious endeavor. Our partnership with Delphi will accelerate the time to market and enable customers to adopt Level 4/5 automation without the need for huge capital investments, thereby creating a formidable advantage for them. 

It's hard out here for a retailer

While new vehicle sales continue to test record highs (though they may be peaking), it hasn't been as great of a year for many retailers. Add to this list shares of Dollar General (NYSE:DG), which was one of the worst performers in the S&P 500 this week, with shares declining roughly 16%.

Despite the plunge in stock price, the company managed to ever-so-slightly increase comparable-store sales by 0.7% during the second quarter, compared to the prior year. That helped drive total revenue 5.8% higher to $5.39 billion, which was a bit short of estimates calling for $5.49 billion.

In reality, it was a bag of mixed results as traffic declined during the quarter, which is a bad sign, but that was offset by higher average transactions. And while earnings per share managed to increase 14% to $1.08, it fell a penny short of analysts' estimates.

On the bright side for investors, management maintained its earnings-per-share guidance of 10% to 15% for the full year -- which is being boosted by share buybacks -- and CEO Todd Vasos promised forthcoming plans to drive same-store sales growth higher and control expenses. 

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.