The Standard & Poor's 500 index has jumped some 20% from its April low, but the trauma of the 10%-plus sell-off is still with us.

Want some proof? Look at what happened Friday when President Trump threatened to boost tariffs to 50% on imports from the European Union and add 25% tariffs on iPhones imported from India.

💵💰This Memorial Day, get $100 off TheStreet Pro — our best deal of the summer won’t last long! Your portfolio will thank you! 💰💵

The S&P 500 fell 0.7%. The Dow was off 0.6%. The Nasdaq Composite and Nasdaq-100 indexes were down about 1% each.

Information technology stocks tumbled 1.3%. Apple  (AAPL)  fell 3% (and 7.6% for the week), and its market capitalization dropped under $3 trillion.

That's why Jay Woods, chief global strategist with Freedom Capital Markets, thinks investors need to be patient over the next few months.

There are important earnings coming up this week and other events in the next few months that can whipsaw markets, Woods said this week in an interview with Chris Versace, columnist and portfolio manager of theStreet Pro.

The interview is part theStreet  Pro's "Stocks and Markets" podcast series.

• Watch the complete interview here.

The U.S. market has seen a big runup since bottoming in early April, and it's a bit frothy.

The Nasdaq saw its relative strength index top 70 — an overbought signal — for four days ending on May 19.

The S&P 500 came within 3% of a new high on May 19 and now looks like it needs to bounce off its 200-day moving average, now about 5,773, to boost investor confidence.

Plus, it's not clear when the tariff battles will end. One reason for the 50% tariff threat on the European Union is the Trump Administration thinks the progress on trade talks is too slow.

Related: Hedge-fund manager sees U.S. becoming Greece

Woods has been working on Wall Street for 20-plus years after graduating from Fordham University. His career includes time spent as a floor trader on the New York Stock Exchange.

By training, he is a technically-minded analyst and starts any analysis by understand financial charts and moving on to the fundamentals.

Here are the key challenges Woods said markets and investors face:

Nvidia  (NVDA) , the high-end chip maker, reports second-quarter earnings after Wednesday's close, and Woods said the company hasn't been rewarded for the strong earnings it has reported in recent quarters.

Nvidia is the developer of graphic processing units that are key to making artificial intelligence work.

Related: Veteran fund manager sends hard-nosed message on Fed interest rate policy

The stock closed Friday at $131.29. But it hasn't come close lately to its 52-week high of $153.13, reached on Jan. 7.