PROVIDENCE, Rhode Island/NEW YORK, Feb 24 (Reuters) - The State of the Union speech from President Donald Trump on Tuesday evening comes at a pivotal point for investors, sideswiped by market turbulence in recent months and craving stability. Days ‌after the Supreme Court overturned Trump's emergency-powers tariffs, market participants are preparing for a speech that could touch on potentially market-moving policies, from ‌trade to affordability to Iran.