By Wallace Witkowski and Victor Reklaitis, MarketWatch

Nasdaq-100 briefly touched intraday record high, before ending lower

U.S. stocks on Monday closed essentially flat, after trading firmly higher, in a volatile session ahead of the start of a pair of closely watched central-bank policy meetings.

Earlier in the session, gains in crude-oil futures and a report showing a surge in home-builder confidence appeared to help lift the equity benchmarks, but those advances evaporated late in the day.

The S&P 500 slipped 0.04 points to close at 2,139.12, after trading within an 18-point range. Telecom and health-care stocks weighed on the index, while utilities and financials led gainers.

Home-builder stocks were among the biggest gainers. PulteGroup, Inc.(PHM) rose 1.5%, D.R. Horton Inc.(DHI) advanced 1.6%, KB Home(KBH) jumped 2.8%, and the iShares U.S. Home Construction ETF (ITB) finished up 0.9%.

Home-builder confidence rose in September, equaling its highest reading in a decade (http://www.marketwatch.com/story/home-builder-confidence-roars-to-a-cycle-high-in-september-nahb-says-2016-09-19). The National Association of Home Builders' index jumped six points to 65 in September.

The Dow Jones Industrial Average closed down 3.63 points at 18,120.17, with shares of Merck & Co.(MRK) and Intel Corp.(INTC) leading the average lower. The blue-chip gauge had been up by as much as 131 points earlier and traded within a 162-point range.

Meanwhile, the Nasdaq Composite Index declined 9.54 points, or 0.2%, to close at 5,235.03. Earlier, the index had been up by as many as 37 points and traded with a 58-point range. An gauge of the largest 100 companies on the tech-laden index, the Nasdaq-100, touched a an intraday record of 4,843.76, before slipping 0.5% to close at 4,796.07.

Market participants mostly focused on the Federal Reserve's policy meeting beginning Tuesday. The vast majority have ruled out a possible rate increase at this point, according to Jack Ablin, chief investment officer at BMO Private Bank. CME Group's FedWatch tool (http://www.cmegroup.com/trading/interest-rates/countdown-to-fomc.html) indicates a 12% probability of a September rate increase.

"The markets are now waiting for evidence that the economy and third-quarter earnings growth are improving," Ablin said.

Read: Talk of surprise hike in the air as Fed meets (http://www.marketwatch.com/story/talk-of-surprise-hike-in-the-air-as-fed-meets-2016-09-19)

Apart from the Fed meeting, analysts also are fretting about announcements from the Bank of Japan, which is holding its two-day policy meeting during the same period as the Fed.

Read: How a 'twist' by the Bank of Japan could upstage the Fed (http://www.marketwatch.com/story/how-a-twist-by-the-bank-of-japan-could-upstage-the-fed-2016-09-17)

"Ahead of these meetings a lot of this action is just noise," said Peter Boockvar, chief market analyst at The Lindsey Group. "We know who has been driving the stock-market bus and these are two very important meetings, and with the Bank of Japan we might see a central bank reversing itself [on easing] and wanting to steepen the yield curve," Boockvar said

The S&P 500 "held up within a zone of support in the 2100-2135 area last week, but we think this level may be in jeopardy of being broken this week as investors anticipate the Fed meeting," said Katie Stockton, BTIG's chief technical strategist, in a note.

Read more:Central bank developments are only game in town for markets (http://www.marketwatch.com/story/central-bank-developments-only-game-in-town-this-week-2016-09-16)

The U.S. oil benchmark (http://www.marketwatch.com/story/oil-prices-rise-due-to-trouble-at-libyas-oil-ports-2016-09-19) pared an earlier advance to settle up 27 cents at $43.30 a barrel. The earlier jump followed news that military conflicts in Libya had affected that country's crude exports.

Another supportive factor for oil was Venezuelan President Nicolás Maduro, who on Sunday said members of the Organization of the Petroleum Exporting Countries and non-OPEC nations were nearing an agreement that would stabilize oil markets.

Asian markets "began the week on a moderately positive tack for equity markets, as the oil price rebounded slightly on reports over the weekend of a potential OPEC deal," said Ian Williams, a Peel Hunt strategist, in a note.

Other key oil industry players had damped expectations over the weekend (http://www.marketwatch.com/story/oil-output-limits-unlikely-at-algeria-meeting-opec-members-say-2016-09-18) for an agreement to limit crude output.

See:Why the S&P 500 could drop for a few weeks, then pop higher (http://www.marketwatch.com/story/why-the-sp-could-drop-for-a-few-weeks-then-pop-higher-in-one-chart-2016-09-19)

Other markets: European stocks closed higher, while a key dollar index pulled back, and gold futures (http://www.marketwatch.com/story/gold-bounces-from-3-month-lows-as-dollar-advance-proves-vulnerable-2016-09-19) advanced 0.6% to settle at $1,317.80 an ounce. A weaker dollar usually provides a pathway for dollar-priced assets like oil and gold to rise, making them cheaper to buyers using other monetary units.

Economic news: Shifting expectations for the two-day meeting of the Fed's rate-setting committee that ends on Wednesday have been a primary driver for U.S. markets. But headlines out of Tokyo due a few hours before the Fed news could be equally or even more important (http://www.marketwatch.com/story/how-a-twist-by-the-bank-of-japan-could-upstage-the-fed-2016-09-17) for asset prices, analysts said.

See:How a 'twist' by the Bank of Japan could upstage the Fed (http://www.marketwatch.com/story/how-a-twist-by-the-bank-of-japan-could-upstage-the-fed-2016-09-17)

Check out:

Corporate news: Shares in Infoblox Inc.(BLOX) closed up more than 15% following news that private-equity firm Vista Equity Partners plans to buy the network security company (http://www.marketwatch.com/story/infobloxs-stock-soars-after-buyout-deal-valued-at-16-billion-2016-09-19) in a $1.6 billion deal.

Tech products distributor Avnet Inc.(AVT) gained 6.8% after Tech Data Corp.(TECD) announced a $2.8 billion deal to buy an Avnet business (http://www.marketwatch.com/story/avnets-stock-jumps-after-28-billion-deal-to-sell-assets-to-tech-data-2016-09-19). Tech Data shares jumped 22%.

Apple Inc.(AAPL) shares declined 1.2% following a Consumer Reports assertion that the cameras on the company's iPhone 7 aren't much better (http://www.marketwatch.com/story/apples-new-iphone-7-cameras-dont-live-up-to-the-hype--consumer-reports-2016-09-19) than those on the previous model.

U.S.-listed shares in Sanofi(SAN.FR) (SAN.FR) edged up 0.7% following news the French drug giant has filed a lawsuit (http://www.marketwatch.com/story/sanofi-files-us-suit-against-merck-over-patents-2016-09-19) against rival Merck & Co.'s (MRK) international unit for alleged patent infringement.

Shares of Sarepta Therapeutics Inc. (SRPT) finished up 74% (http://www.marketwatch.com/story/sarepta-stock-jumps-82-on-approval-of-controversial-duchenne-muscular-dystrophy-drug-2016-09-19) after the Food and Drug Administration granted its Duchenne muscular dystrophy drug--the first treatment for the degenerative disease--accelerated approval.

Shares of GoPro Inc.(GPRO) advanced 2.3% after the action-camera maker unveiled a new camera and its first drone (http://www.marketwatch.com/story/gopro-debuts-drone-as-it-unveils-new-cameras-2016-09-19).

The leader of the union representing auto workers in Canada said thousands of factory employees will strike (http://www.marketwatch.com/story/gm-workers-in-canada-will-strike-if-monday-deadline-missed-says-union-leader-2016-09-19) at two General Motors Co.(GM) plants if the sides miss a Monday night deadline for a new contract. However, GM shares rallied 2.4%, after Morgan Stanley upgraded the stock to overweight from equal-weight and raised the price target to $37 from $29 a share.

(END) Dow Jones Newswires

September 19, 2016 16:39 ET (20:39 GMT)