June 22 (Reuters) - The Standard & Poor's 500 and Nasdaq Composite indexes closed lower on Monday, with shares of tech giants including Alphabet declining as investors assessed developments in negotiations between the United States and Iran.

The Dow Jones Industrial Average ended the day higher, supported by the healthcare and industrial sectors.

SpaceX shares plummeted, dragging down the Nasdaq Composite Index. The company, led by billionaire Elon Musk, issued its first bond on Monday, indicating that as of June 19 it had approximately $100.8 billion in cash and cash equivalents.

Optimism about artificial intelligence has helped support Wall Street's recent rally, but analysts have noted that a growing number of investors are becoming concerned about massive spending by cloud computing giants on expanding their infrastructure.

Shares of Alphabet fell sharply, and shares of Meta, Amazon and Microsoft also declined.

Bill Northey, senior investment manager at U.S. Bank Wealth Management, said, "This is a sector that is largely driven by sentiment, and its stocks tend to move collectively on a daily basis."

He added, "But looking at the bigger picture... some of the strongest foundations lie in the field of AI data center building. This includes both the cloud computing giants and a number of components that go into this ongoing building process."

According to preliminary data, the Standard & Poor's 500 index fell 25.41 points, or 0.34 percent, to 7475.17 points, and the Nasdaq Composite index declined 339.67 points, or 1.28 percent, to 26178.26 points.

The Dow Jones Industrial Average rose 162.36 points, or 0.29 percent, to 51,727.06 points.