NEW YORK (TheStreet) -- The tides turned on Monday as the prospect of a Greek debt deal finally looked like a possibility. That helped to prop up markets to begin the new week on better footing after a dour end to Friday's session. 

The S&P 500 was up 0.61%, and the Dow Jones Industrial Average gained 0.53%. The Nasdaq added 0.72%, notching a new record close of 5,153.

Increased M&A talk in the health care sector also supported a rally on Monday. Cigna (CI) rejected Anthem's (ANTM) increased offer of $184 a share after its board unanimously opposed the terms. The new offer from Anthem had represented a 35.4% premium over Cigna's late May price before reports of a deal surfaced.

The health care sector has been the focus of M&A talk for the past few weeks, including potential matchups between Aetna  (AET) and either Humana (HUM) or UnitedHealth (UNH). The Health Care SPDR ETF (XLV) gained 0.78% on Monday.

Greek Prime Minister Alexis Tsipras submitted new proposed reforms over the weekend, which were a condition of further debt relief. Among the reforms reported, though not confirmed, Greece will eliminate early retirement benefits, cut defense spending and increase corporate tax rates.

Eurozone finance ministers had convened for an emergency summit in which to discuss Greece's future in the eurozone at a political level. Talks have escalated as Greece faces a crucial repayment to the International Monetary Fund by the end of the month.

U.S. existing home sales rose 5.1% to 5.35 million in May, the fastest pace since 2009. The share of first-home buyers increased to 32% from 30%. Economists had expected the May rate to increase to 5.25 million, up from a revised pace in April of 5.09 million.

"This was a very constructive report and it suggests that the U.S. housing market recovery is back on track after the missteps earlier this year," said Millan Mulraine, deputy head of U.S. strategy at TD Securities. "The shift in the sales mix in favor of first-time buyers is a healthy development, and it points to a more solid foundation for the housing recovery going forward."

Fitbit (FIT) extended gains achieved since the company's trading debut last Thursday. Shares added 14.7% to $36.94. The initial public offering of San Francisco-based Fitbit was priced at $20 a share. Click here for more.

Sequential Brands (SQBG) announced that it has agreed to acquire Martha Stewart Living Omnimedia (MSO) for $6.15 a share in a cash-and-stock deal. Martha Stewart shares gave back 12.5% on Monday after rallying last Thursday once news broke of deal talks.

Tesla (TSLA) moved 1% lower on reports production of the Model 3 electronic car had been delayed to 2018, according to Inside EVs and reported by Bloomberg. A Tesla spokesperson reiterated a previous 2017 timeline. Click here for more.

Oil and gas company Williams (WMB) rocketed 26% higher after Energy Transfer Equity (ETE) confirmed it had made an unsolicited bid worth $48 billion. Williams rejected the offer.

Facebook (FB) climbed nearly 3% on reports is encroaching on Google's (GOOGL) YouTube in terms of market share for online video advertising. Research firm Apere estimated Facebook has an audience size of 1.4 billion monthly active users compared to YouTube's 1.3 billion.

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