Maybe the best thing the president can do for Wall Street is go away.

Stocks rallied last week as Donald Trump took part in his first international trip as president. The S&P 500 reached an all-time high, and volatility brushed multi-year lows as Trump rubbed elbows in the Middle East, ruffled feathers in Europe and largely steered clear of off-the-cuff outbursts on Twitter.

The Nasdaq climbed 2.08% last week to 6,210.19, marking its second-best week since Trump's inauguration. The only week the index saw a better performance was that of April 23, on the heels of the first round of the French presidential election and when Congress reached a short-term deal to avoid a government shutdown.

The S&P 500 rallied 1.43% last week to 2,415.82, marking its third-best week since the inauguration. And the Dow gained 1.32% to 21,080.28, its fourth-best week under Trump's presidency.

The CBOE Volatility Index, which measures volatility, floated downwards. The so-called investor fear gauge jumped in the wake of reports that the president had asked former FBI director James Comey to stand down on an investigation into Michael Flynn. But last week, it settled back down to near multi-year lows.

As to whether Trump's absence had an effect on Wall Street, Compass Point LLC analyst Isaac Boltansky said it's always tough to tell but left the door open to the possibility.

"I can tell you that my client calls last week were focused on the tax reform hearing and health care timelines," Boltansky said. "The week before was special prosecutors and Russia."

To be sure, the idea that less activity in Washington bodes well for markets isn't a new one. Hedge fund manager Eric Singer has theorized about the "Congressional effect," finding that the S&P 500 performs better on days when Congress is out of session than when it is in. Congress is in recess this week.

The days leading up to Trump's trip were highly tumultuous, with near daily reports coming out of outlets such as the New York Times and Washington Post detailing new revelations on Trump, Russia and related investigations. Minutes after the president took off for Saudi Arabia on May 19, the Times and the Post published a pair of reports on the Russia investigation and Comey firing.

But in Trump's absence, it was largely back to business as usual in Washington. Lawmakers spent much of the week debating the White House budget, rolled out while Trump was on the road, and debating the ins and outs of tax policy.

Meanwhile, Trump's foreign trip with stops in the Middle East and Europe was relatively drama-free. His visit to Saudi Arabia coincided with a number of business deal announcements there, and while his time with fellow NATO leaders was not entirely seamless, there were no major gaffes, either. Perhaps more importantly, the president largely stayed off of Twitter and appeared unable to consumer his usual diet of cable news.

In the U.S., buzz began to surge of an overhaul at the White House following Trump's return. The White House is reportedly weighing bringing in a crisis management team to handle matters related to the Russia investigation and shake up top staff. The Wall Street Journal reported that the administration is even considering having a lawyer vet Trump's tweets.

But if such a plan is under consideration, it doesn't look like it's been implemented, judging by the president's social media activity since his return.

Since getting back to the United States over the weekend, the president has put out a slew of tweets attacking the media, brushing aside the Russia investigation and slamming Obamacare. On Tuesday morning, he took a swipe at Germany on trade and called on the U.S. Senate to change its legislative rules to pass laws with a simple majority. Major indexes declined.