Updated from 5:56 a.m. EDT
 
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Here are five things you must know for Tuesday, May 23:
 
1. -- The deadly attack at an Ariana Grande concert at the Manchester Arena late Monday has claimed 22 lives and is being treated as a terrorist incident, a spokesman for the Greater Manchester Police confirmed. 

Police said the attacker died at the scene of the incident, which took place Monday night at the end of the concert in central Manchester, about 160 miles northwest of London. The attacker used a self-detonating explosive in the 21,000-seat capacity arena, police said, and noted that inquiries at this stage were focused on whether he acted alone or with the assistance of others.

"We have been treating this as a terrorist incident and we believe, at this stage, the attack was conducted by one man," Greater Manchester Police Chief Constable Ian Hopkins said in a statement. "The priority is to establish whether he was acting along or part of a network." 
 
There was no immediate claim of responsibility, but Hopkins said police were treating the blast as an act of terrorism "until we know otherwise."
 
As many as 60 people also were hurt in the blast. Hopkins said some of the dead were children but provided no further details.
 
European stocks were trading higher Tuesday despite the explosion. The dollar index, a measure of the greenback's strength against a basket of six global currencies, declined 0.12% to 96.87, the lowest since early October.
 
U.S. stock futures pointed to gains ahead of the opening of trading on Wall Street.
 
2. -- The White House hopes to sell its 2018 budget proposal as a "taxpayer first" plan that makes deep cuts to a number of programs while raising spending on border security and defense. 

The Trump administration will send the budget proposal to Congress on Tuesday, outlining its wish list for how the federal government will spend its money next year. The plan, titled "A New Foundation for American Greatness," will include $3.6 trillion in spending reductions by slashing funds for entitlements and discretionary programs while increasing allocations for items including law enforcement, defense and school choice. About $600 billion in cuts would be made to Medicaid over the next decade, while cuts to food stamps would amount to $193 billion over 10 years.

Office of Management and Budget Director Mick Mulvaney, in a call with the press on Monday, sought to cast the proposal as one that focuses on where funds are coming from instead of how they're being spent.
 
"If I had a sort of subtitle for this budget, it would be 'the taxpayer first budget,'" he said, adding that he believes this is the first time in a long time an administration has written a budget "through the eyes of the people who are paying the taxes."
 
The budget will call for billions of dollars of cuts to food stamps and disability insurance and an $800 billion reduction in spending on Medicaid. It also will call for requiring those seeking child care and earned income tax credits to provide social security numbers to collect them, a measure intended to block undocumented immigrants from benefiting from such credits.
 
"There's a certain philosophy wrapped up in the budget, and that is that we are no longer going to measure compassion by the number of programs or the number of people on those programs," Mulvaney said. "We're going to measure compassion and success by the number of people we help get off of those programs to get back in charge of their own lives." 

3. -- Nokia (NOK - Get Report)  shares rose the most in nearly three years Tuesday after the company said it settled an intellectual dispute with Apple (AAPL - Get Report)  and simultaneously signed a multi-year patent license agreement withe the iPhone maker.

The deal will allow the Epsoo, Finland-based networking company to provide infrastructure products to Apple, while Apple will resume carrying Nokia's digital health products in its online and retail stores. Nokia also will receive an undisclosed cash payment from Apple.
 
"This is a meaningful agreement between Nokia and Apple," said Nokia's chief legal officer, Maria Varsellona. "It moves our relationship with Apple from being adversaries in court to business partners working for the benefit of our customers." 

Nokia shares rose 6.8% in trading in Paris, the biggest single-day increase since July 2014.

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4. -- Homebuilder Toll Brothers (TOL - Get Report)  reported fiscal second-quarter earnings of 73 cents a share, topping analysts' forecasts of 62 cents.

Revenue in the quarter was $1.36 billion, which also beat estimates. The stock rose 2.6% in premarket trading.

Earnings are also expected Tuesday from AutoZone ( AZO) , DSW ( DSW) , Cracker Barrel ( CBRL - Get Report) , Container Store ( TCS - Get Report) , Intuit ( INTU - Get Report) and Take-Two Interactive ( TTWO - Get Report) .