Title: Market Turbulence: Impact of Apple's Event, Stock Declines, and Trump's COVID Diagnosis on U.S. Stocks

This piece provides an insightful overview of the recent movements in the U.S. stock market, covering three significant events that influenced stock prices. Firstly, it delves into Apple's latest hardware event at its Cupertino campus, marking its first such event since reaching a $1 trillion valuation. The event saw the unveiling of new products including the iPhone XS, iPhone XS Max, and Apple Watch Series 4. Despite these announcements, the broader stock market experienced a sharp decline on Friday morning, reversing gains from a mid-week rally. The year 2020 is highlighted as a challenging one for publicly traded equities, with the stock market facing volatility. Adding to the uncertainty, President Donald Trump's diagnosis with COVID-19 has investors on edge, pondering the potential impact on asset prices. The situation underscores the skittish nature of the U.S. stock market amidst health concerns and economic indicators.

Subtopics:
- Apple's hardware event and its impact on stock prices
- Sharp decline in U.S. stock market indices on Friday morning
- Uncertainty in the stock market following President Trump's COVID-19 diagnosis