U.S. stock futures fell on Monday after Greeks resoundingly rejected creditors' conditions for further financial aid, pushing their country closer to bankruptcy and a potential exit from the eurozone.

S&P 500 futures declined 19 points, or 0.9%, to 2050. E-mini Dow futures dropped 167 points, or 1%, to 17482, and e-mini Nasdaq-100 futures lost 41 points, or 0.9%, to 4388. Changes in stock futures don't always accurately predict moves in the stock market after the opening bell.

The declines come after more than 61% of Greek citizens voted "no" in Sunday's referendum on the terms for a bailout that included pension cuts, tax increases and other measures. The referendum was on whether to accept austerity terms demanded by the country's creditors in exchange for further aid. The "no" vote appeared to increase the likelihood that Greece may eventually exit the eurozone.

Entering the weekend, many investors anticipated the result of the Greek referendum to be a "yes" vote, which European leaders had encouraged.

"What most banks and research shops were predicting was that the measure would pass, Greece would take some of its tough medicine and move on," said Erik Wytenus, global investment strategist at J.P. Morgan Private Bank. "It's not good to have this uncertainty. It's not good to have this destabilizing force. But we would not expect any selloff in U.S. stocks to be a substantial one or that this will cause a correction in U.S. stocks."

Stocks and bonds in Europe fell on Monday, but the decline was fairly muted. The Stoxx Europe 600 lost 1%, while Germany's DAX fell 1.6% and France's CAC-40 dropped 1.9%. The euro initially tumbled before paring losses, recently trading 0.8% lower against the dollar at $1.1026.

Investors bought U.S. Treasurys, viewed as havens, on Monday, pushing down the yield on the 10-year note to 2.304% from 2.393% on Thursday. Bond yields fall as prices rise.

Earlier Monday Greece's confrontational finance minister Yanis Varoufakis resigned, which many investors viewed as a positive sign for negotiations with creditors. "The prospect for a deal is better now that he's out," said Mr. Wytenus. "That's helping some of this market reaction."

The drama surrounding the Greek debt crisis has dominated U.S. stock trading over the past several weeks. Two weeks ago, on June 22, stocks around the globe climbed as negotiations between Greece and its international creditors appeared to be moving closer to a positive conclusion. However, a week later, on June 29, stocks tumbled as talks broke down. The Greek stock market was closed for the week ahead of the referendum on Sunday, and there aren't plans to reopen it until Tuesday at the earliest.

Analysts have said that even with the recent tumult in global markets, they expect stocks to hold up better than they did in 2011 and 2012 when fears of a Greece bankruptcy swelled into worry about the financial stability of other struggling European economies, such as Spain and Portugal.

Unlike several years ago, now little of Greece's government debt is held by banks and private investors outside of the country, which lessens the likelihood of a ripple effect of losses.

After the developments over the weekend, analysts said the probability that Greece eventually exits the eurozone is now much higher. However, they said with Europe's improving economy, they remain bullish on the region.

Mr. Wytenus said he is telling clients to keep calm, look through all the geopolitical noise, and buy European stocks.

"No matter what happens with Greek negotiations this week, the economic situation on the ground is much more improved than in 2012 when people were concerned if Greece went out, it would create a domino effect," he said. "Even if we were to see further weakness throughout the course of the week, we'd continue to advocate for clients to buy Europe."

Write to Corrie Driebusch at corrie.driebusch@wsj.com

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