The year's first three months ended officially on Thursday, and the returns were good: the Dow Jones Industrial Average was up 6.4 percent, while the S&P 500 added 5.4 percent and the Nasdaq Composite 4.8 percent.

Another day of modest gains Friday took all three indices to just shy of new highs in their two-year bull run: the Dow ended the week at 12,376.72, the S&P at 1,332.41, and the Nasdaq at 2,789.60.

The first quarter was rocky, but uprisings across the Arab crescent that left two venerable leaders ousted and sent oil prices skyrocketing left little trace on the markets.

Neither did the massive earthquake-tsunami double punch that shocked Japan on March 11, leaving more than 28,000 dead or missing and forcing shutdowns in key industries.

Instead, a steady flow modestly positive data for the economic recovery has fed the bulls.

Exports are growing steadily, and data released Friday showed another drop in the unemployment rate, to 8.8 percent. That confirmed that the private sector is adding jobs at a steady pace.

Meanwhile a key determinant of the Federal Reserve's interest rate-setting policy, core inflation, remains subdued.

So few expect that US rates will rise anytime soon, even as the European Central Bank appears poised to push up rates there.

For the first quarter most sectors moved in tandem with the key indices. But tech stars were notably absent from the run: Google, Microsoft, Amazon, Intel and Cisco were all down for the period, and it was mainly Apple and Oracle that kept the Nasdaq above water.

For the week to Friday, investors also dismissed the fiscal fate of Europe's most troubled economies -- Greece, Portugal, Ireland and Spain.

Merger and acquisition activity was the focus instead: Canadian firm Valeant Pharmaceuticals (+18.5 percent for the week) made an unsolicited $5.7 billion cash bid for biotech firm Cephalon (+31.3 percent).

General Electric (+3.0 percent for the week) announced it was buying French group Converteam, which specializes in electrification and automation equipment, for $3.2 billion.

International Paper (+9.5 percent) will pay $423 million for a stake in an Indian paper company.

And topping off the week, US bourse operators Nasdaq (+11.6 percent) and ICE (-6.4 percent) made a hostile bid for NYSE Euronext (+14.9 percent), which could sabotage NYSE's plan to merge with German powerhouse Deutsche Bourse.

Another big stock in the news was longtime investor favorite Berkshire Hathaway, which fell under a cloud after Warren Buffett's heir apparent David Sokol suddenly resigned.

The resignation announcement noted that he had invested in the shares of Lubrizol before Berkshire made its March takeover of the company, but Buffett insisted in a statement that Sokol's investments were not illegal and did not relate to the resignation.

Berkshire's B shares were down 1.8 percent for the week.

But amid the bullishness, April 1 came in with no-joke warnings over economic weaknesses, pointing to stagnant wages and the possible double-dip recession in the housing market.

"The biggest threat to the long-term health of the economy would be a slowdown in payrolls," said analysts at Briefing.com.

"If job growth suddenly slows, income growth will undoubtedly suffer and consumption growth will weaken along with it."

Wells Fargo Securities also issued a reality-check.

"While these (job) reports are encouraging, consumer confidence painted a far more cautious picture," they warned.

"Consumer confidence dropped sharply in March to its lowest level since December. ... Rising gasoline prices and uncertainty on Japan and the Middle East likely helped drive the significant decline."

New indicators of the pace of growth next week will include the release Tuesday of minutes from the Federal Reserve's last meeting -- which give an idea how they feel about the threat of inflation.

Also on Tuesday, the ISM index on the services industry comes out.