U.S. stocks came under selling pressure Thursday morning, as renewed tensions between Russia and Ukraine as well as mixed earnings and economic data sparked a flight to safe assets, such as Treasurys and gold.

The S&P 500 (SPX) opened 5.5 points, or 0.3%, lower at 1,976.11. The Dow Jones Industrial Average (DJI) lost 39 points, or 0.2%, to 17,099.36 at the open, retreating from Wednesday's record close.

The Nasdaq Composite (RIXF) began the day with a loss of 12 points, or 0.3%, to 4,413.85.

Among corporate news, Microsoft announced plans to cut up to 18,000 jobs, sending its shares higher. Morgan Stanley's quarterly results topped expectations, but both Mattel and AutoNation were suffering following disappointing earnings.

In economic news, the number of people who applied for jobless benefits fell to the lowest level in nine weeks. But construction on new U.S. homes was far weaker than expected, tumbling to the slowest pace in nine months.

A July reading on activity among regional manufacturers is slated for release at 10 a.m. Eastern by the Federal Reserve Bank of Philadelphia. Economists expect to see the result weaken to 16.5 from 17.8 in June, which was the highest level since September.

Investors woke up to renewed geopolitical risks after news reports that a Ukrainian fighter jet was shot down by missiles from a Russian plane. On Wednesday, the U.S. unveiled a new round of sanctions against Russia, targeting companies such as oil giant Rosneft and Gazprombank ONO. The European Union said it will detail new sanctions against Russia by the end of this month. European stocks fell sharply on Thursday. Read: Russian stocks pounded after U.S. imposes new sanctions.

Morgan Stanley rises; Mattel sinks

In earnings news, shares of Morgan Stanley (MS) gained 1.3% after the company's profit and revenue for the second quarter beat Wall Street's projections.

Blackstone Group L.P. (BX) reported stronger-than-expected second-quarter earnings on the back of gains from asset sales in its private-equity business. The shares rose 2.7%.

Mattel (MAT) shares sank 7.8% as quarterly earnings were dragged lower by muted sales of Barbie dolls.

SanDisk (SNDK) shares fell 7.8% after the flash-memory maker's third-quarter revenue forecast was lighter than anticipated. Read more about the day's notable movers here.

Investors will monitor comments from St. Louis Fed President James Bullard, who is slated to speak in Kentucky about monetary policy at 1:35 p.m. Eastern Time. Bullard said in a Bloomberg interview last week that a continued decline in U.S. unemployment could push inflation above the Fed's 2% target by the end of 2015. Bullard isn't a voting member of the Fed's policy-making committee.

After trading closes Thursday, Google (GOOG) is expected to post earnings of $6.25 a share on revenue of $12.3 billion. Read NEED TO KNOW: Janet Yellen might disagree, but Amazon tapped as screaming buy.

In the commodities market, August crude-oil futures (CLQ4) rose $1.32 to $102.52 a barrel, and gold futures (GCQ4) picked up $1.40 to $1,301 an ounce.

Asian stocks overnight closed mixed, with Japan's Nikkei Average down 0.1%.