The S&P 500 will rocket 18% by year-end as the economy stays strong and the Fed ends interest rate hikes, Oppenheimer investment chief says

• The S&P 500 could soar another 18% by year-end, according to Oppenheimer. 
• That's because the economy is strong and the Fed is likely to end its rate hike cycle. 
• While 5% Treasury yields have sparked concern among investors, that's normal compared to previous eras. 

The S&P 500 is due for a monster rally by the end of the year, as the Federal Reserve looks poised to dial back its war on inflation, according to Oppenheimer's chief investment strategist John Stoltzfus.