Stocks Are Sliding

Stocks are lower to start this particularly busy week.

The Dow is down 68 points, the S&P 500 is down 9 points, and the Nasdaq is down 26 points.

The biggest news of the day so far is two notable mergers: Dollar Tree's deal to acquire Family Dollar and Zillow's deal to acquire Trulia.

Dollar Tree announced it will acquire Family Dollar for $74.50 per share in a deal that will create a combined company with annual sales of more than $18 billion. The deal comes after activist investor Carl Icahn took a 9.4% stake in Family Dollar and urged the company to seek a sale.

Following the announcement, Dollar Tree shares were up 5% while shares of Family Dollar were up 22%.

Zillow announced it will acquire Trulia in a $3.5 billion all-stock deal that values Trulia at a 25% premium to its closing price on Friday. Last Thursday, Bloomberg reported that Zillow was seeking to acquire Trulia.

Following the deal, Zillow shares were down 5% while Trulia shares were up 8%.

Also in stock news, shares of El Pollo Loco, which made their market debut on Friday, were up more than 25% after gaining 50% on Friday.

On the economic data front, Markit's "flash" reading for July services data was unchanged from last month at 61, which also topped expectations for a reading of 59.9.

Pending home sales for June fell 1.1%, missing expectations for a 0.5% increase.

It's also a busy week for earnings, with Herbalife among the notable companies set to report after today's market close.