Although we don't believe in timing the market or panicking over daily movements, we do like to keep an eye on market changes -- just in case they're material to our investing thesis.

Following their best week of 2014, U.S. stocks opened lower on Monday, with the benchmark S&P 500 and the narrower Dow Jones Industrial Average (^DJI -0.93%) down 0.06% and 0.17%, respectively, at 10:15 a.m. EST. Technology stocks Apple (AAPL 0.06%) and Yelp (YELP -0.43%) are in the news this morning. Meanwhile, new Federal Reserve Chairwoman Janet Yellen can expect scrutiny this week from investors and Congress.

Ten days into her new job, Yellen is set to deliver her first semiannual testimony on monetary policy to Congress, appearing before the House Financial Services Committee on Tuesday and the Senate Banking Committee on Thursday. As the unemployment rate falls toward the 6.5% level the Fed established as a milestone before it would consider raising interest rates, investors will be looking to see if Yellen offers a more nuanced road map that would account for a mixed picture on employment. The drop in the participation rate -- people leaving the workforce -- has been instrumental in lowering the unemployment rate; former Fed Chairman Ben Bernanke had already suggested that rates could stay at zero "well after" the jobless rate reached 6.5%.

Shares of online city guide Yelp are up nearly 4% at 10:15 a.m. EST on a Wall Street Journal report on a partnership that will see Yahoo! include Yelp's listings and reviews of local businesses in its search results. The terms of the deal are not known, but it clearly serves to raise Yelp's profile; whether it adds significantly to the company's value is a different matter altogether. As the Journal's "Heard on the Street" column recently noted, "as a business, Yelp does have good growth potential. Its stock looks like it's already there." Yelp's enterprise value (market capitalization and net cash) is equal to more than 16 times next 12 months' revenue estimate.

Influential proxy advisory service Institutional Shareholder Services (ISS) is giving Apple the nod in its dispute with Carl Icahn over the activist investor's proposal that the iPhone maker increase its share repurchase program by $50 billion. In its note, ISS argued that "the [Apple] board's latitude should not be constricted by a shareholder resolution that would micromanage the company's capital allocation process." Apple shareholders will vote on Icahn's motion at the annual meeting on Feb. 28.

That's the same position that another legendary investor, Berkshire Hathaway CEO Warren Buffett, espoused in an interview with CNBC last October. Between the news that Apple had repurchased $14 billion of its own shares since its Jan. 18 earnings report and ISS' position, the odds of Icahn's proposal gaining shareholder approval look poor. That's no bad thing; note, however, that ISS criticized Apple for not outlining a strategy regarding the growing cash mountain it is accumulating overseas, which it cannot repatriate without a incurring a tax. ISS wrote that "given the rate at which the percentage of offshore cash is growing, moreover, a strategy which goes no further than returning the excess domestic cash will soon become inadequate." Fair comment. Apple CEO Tim Cook said the company will provide "updates" regarding its share repurchase program to investors in March or April.