US STOCKS-Market ends down on housing data, technicals

* Existing-homes sales unexpectedly fall, homebuilders off

* S&P 500 index ends below key technical level

* Energy shares, facing regulatory uncertainty, drag

* In bright note, Apple rises on iPad sales

* Dow off 1.4 pct, S&P down 1.6 pct, Nasdaq off 1.2 pct

* For up-to-the-minute market news see [STXNEWS/US] (Updates to close)

By Ryan Vlastelica

NEW YORK, June 22 (Reuters) - U.S. stocks fell more than 1 percent in yet another late-day selloff on Tuesday as unexpectedly poor housing figures and the puncture of a key technical level sapped buying interest.

Stocks marked time in a thinly traded session until the S&P 500 fell through its 200-day moving average, which had been a basis of support in the last few days.

Homebuilders' shares fell after the National Association of Realtors reported sales of existing homes unexpectedly fell in May in the latest of a series of weak economic releases.

D.R. Horton Inc (DHI.N) fell 2.9 percent to $10.24 while luxury homebuilder Toll Brothers (TOL.N) was off 2.9 percent at $17.11. The Morgan Stanley housing index .HGX slumped 2.6 percent. For details, see [ID:nN22123277]

"This tells you how weak demand is, and that creates a lot of uncertainty about where the economy is going," said James Meyer, chief investment officer at Tower Bridge Advisors in West Conshohocken, Pennsylvania.

The Dow Jones industrial average .DJI dropped 148.96 points, or 1.43 percent, to 10,293.45. The Standard & Poor's 500 Index .SPX fell 17.86 points, or 1.60 percent, to 1,095.34. The Nasdaq Composite Index .IXIC lost 27.29 points, or 1.19 percent, to 2,261.80.

The S&P 500 ended below 1111.33, the 200-day moving average.

"It's not a good sign," said Bill Strazullo, partner and chief investment strategist at Bell Curve Trading in Boston. "The last line in the sand is 1,050. You break that, it's done. The March '09 rally is over ... it's really critical what's going on here."

Energy companies also numbered among the decliners amid worries about regulation. Oil drillers briefly spiked after a U.S. judge ruled against a six-month moratorium imposed by the White House on deepwater drilling, but the Obama administration said it will immediately appeal, and the sector fell. [ID:nN22147432].

Cabot Oil & Gas Corp (COG.N) shares dropped 6.2 percent to $33.70 and the S&P energy sector .GSPE fell 1.3 percent.

"The markets aren't going to like the uncertainty that the back-and-forth between the courts and the administration creates," said Joe Saluzzi, co-manager of trading at Themis Trading in Chatham, New Jersey.

On the upside, Apple Inc (AAPL.O) rose 1.3 percent to $273.56 on news it had sold 3 million iPads since the product's April launch. In addition, at least two brokerages raised their price targets on the tech bellwether. [ID:nN22130761]

In earnings news, Jefferies Group Inc (JEF.N) reported second-quarter earnings that surged past expectations, lifting the stock 6.3 percent to $24.32. But Walgreen Co (WAG.N) fell 6.6 percent to $28.15 after it reported a weaker-than-expected third-quarter profit. [ID:nN22250346] and [ID:nN22169964]

After the bell, Jabil Circuit Inc (JBL.N), a maker of electronic circuit boards, rose 8.7 percent to $14.77 in extended trading after the company reported its third-quarter results. [ID:nASA00GYR]

Adobe Systems Corp (ADBE.O) rose 1.6 percent to $33.25 in extended trading after reporting its second-quarter results. [ID:nASA00GYT]

Dow component McDonald's Corp (MCD.N) fell 1.4 percent to $68.91. Earlier, the Center for Science in the Public Interest threatened to sue the fast food giant if it doesn't stop using Happy Meal toys to draw children into its restaurants. Burger King Holdings Inc BKC.N fell 1.4 percent to $17.90. [ID:nN22234354] (Editing by Kenneth Barry)