Markets around the world have started to open for business, ushering in the first week that the United States’ credit rating was less than top ranked AAA.What will be the effect on financial markets worldwide? Here is a look at this and other stories that CNN plans to follow this week:

Following U.S. downgrade, world markets worry and wait

The ripple effect from Friday’s downgrade by Standard & Poor's of the U.S. credit rating to AA+ from the top rank of AAA remains to be seen across the world.

Middle Eastern markets, the first to open since the downgrade, were sharply lower on Sunday. Israel's market temporarily halted trading at one point and finished down more than 6%, while the Dubai Financial Market General Index fell 3.7%.

Stocks on key Asian exchanges dropped modestly early Monday.

In early Tokyo trading, the Nikkei index fell 124 points, or 1.3%. Hong Kong's Hang Seng index tumbled 2.6% at the open. And  U.S. stock futures fell around 1.7% in early electronic trading Sunday.

The reaction might end up being muted. The United States is the world's largest economy and remains a good credit risk. Even after a downgrade, the government will likely still be able to pay its bills for years to come.

Still, we can expect uncertainty this week in the financial markets.

"We've never been through this before. People don't know what to expect," said Ted Weisberg of Seaport Securities, who has spent decades on the floor of the New York Stock Exchange. "So you have to be careful."

And the downgrades from S&P probably aren't likely to be over. It's possible that S&P will soon downgrade the debt of mortgage finance giants Fannie Mae and Freddie Mac, along with AAA-rated insurance groups.

Investigation under way in London riots

Authorities were expected to continue with a "major investigation"  launched over the weekend after a vigil turned into a riot against police officers. A crowd mourning a man that was killed by police turned violent Saturday, police said. Troublemakers began tossing petrol bombs and "missiles" at officers and looting stores, London's Metropolitan Police said Sunday.

"The behavior by a criminal minority put police officers, fire brigade personnel and the public at significant risk," Cmdr. Adrian Hanstock said in a statement.

Police were on the streets of London in hopes of preventing any further riots - particularly in Tottenham, the scene of the riots.

Three American hikers await trial verdict in Iran

An Iranian court is expected to issue a verdict in the coming days after a hearing was held last week for three American hikers accused of being spies. Joshua Fattal and Shane Bauer have been held in Iran since their detainment in 2009. Fellow hiker Sarah Shourd was released in September 2010 for medical reasons.

Attorney Masoud Shafiei, who represents the hikers, said he had not heard anything from court officials as of 6:30 p.m. Sunday, a week after a hearing that he hoped would result in a swift and lenient ruling.

On Saturday, state-run Press TV reported that "Iranian Foreign Minister Ali Akbar Salehi expresses hope that the trial of the three U.S. nationals detained on charges of espionage and illegal entry will result in their freedom."

"God willing ... the Judiciary will present necessary information in this respect when the time is right," Foreign Minister Ali Akbar Salehi said during a news conference in Tehran.

Conrad Murray pretrial scheduled for Monday

 A pretrial hearing into the death of megastar Michael Jackson is scheduled for Monday when attorneys will discuss questionnaires that prospective jurors will be asked to fill out.

Conrad Murray, who was hired as Jackson's personal physician as he prepared for his comeback concerts in London, is charged in the singer's death.

It’s been more than two years since Jackson's death, which the Los Angeles coroner ruled was from an overdose of the surgical anesthetic propofol, combined with other drugs.

Jury selection was under way in May when the defense requested a delay so its expert witnesses could have more time to prepare for new experts hired by the prosecution.

The judge in the case then dismissed hundreds of prospective jurors and rescheduled the trial for several months later.

Jury selection in the trial is set to begin on September 8 in a Los Angeles County courtroom, with opening statements later in the month.

Oslo Music Festival to go on

Staring down national fear, anger and tragedy, concert organizers in Oslo, Norway, are going ahead with plans for a five-day music festival this week which will be the first big entertainment event since the bombing and shooting rampage that left scores dead on July 22.

A statement by festival organizers said the aim of having the festivities so close to the time of the massacre was to send a message of resiliency.

“We hope that our events can help ease the sadness and also be good meeting places in the days and weeks to come. We wish to take Oslo back by once again filling it with the great variety of cultural activities this city is known for and also by spreading a clear message that our population wants to take care of each other.”

Artists slated to perform starting Tuesday include Pulp, Kanye West and Guided by Voices.

31 nations to test tsunami warning system Wednesday

Thirty-one nations will test a tsunami early warning system Wednesday for the northeastern Atlantic, Mediterranean Sea and connected seas.

The warning will disseminate from the Istanbul Observatory and Earthquake Research Institute in Turkey and will include sending text messages, e-mails, faxes and other technologies to tsunami centers in the region, according to a news release by the United Nations Educational, Scientific and Cultural Organization.

Participating nations include Belgium, Bulgaria, Greece and Italy, which have all had earthquakes in recent days.

News Corp. to release fiscal report

News Corp. will release its fiscal year-end earnings report Wednesday, likely thrusting embattled chairman and CEO Rupert Murdoch back in the spotlight after a brief respite.

A phone-hacking scandal that has already brought a 168-year-old newspaper to its end and caused a parliamentary investigation in the United Kingdom will likely draw attention to a routine report that is usually only combed over by stockholders.

Organizational questions remain for News Corp. Just this weekend, Murdoch's plans for his daughter to join him and other family members on the News Corp. board were thwarted.  Van Dinh, News Corp. chairman of the Nominating and Corporate Governance Committee, released a statement Friday saying that Elisabeth Murdoch indicated "some weeks ago that she felt it would be inappropriate" to join the company board.

What beams up in Vegas, stays in Vegas

Trekkies from distant worlds, in a sense, will converge on Nevada next weekend for the official Star Trek Convention in celebration of the 45^th anniversary of the space -themed franchise.

Special guests will include Leonard Nimoy and William Shatner, called in convention literature “one of the world's pop culture treasures,” along with several actors from subsequent generations of the show and films.

Israel plans finance team after mass demonstrations

More details are expected to be released this week about a new financial team created by Israeli Prime Minister Benjamin Netanyahu in response to mass demonstrations over the rising cost of living in the Jewish state.

The announcement by Netanyanhu was made after more than a quarter of a million demonstrators took to the streets in public outcry to hard economic times.

"In the recent weeks, we have been witnessing a public protest that expresses our real distress," Netanyahu said at the opening of his weekly Cabinet meeting. "We cannot and we shouldn't ignore the voices coming out of the public, we want to give real solutions and we will do so."

The economic team - comprised of government officials and professionals outside the administration - will focus on reducing the cost of living and changing the country's economic priorities, Netanyahu said.

Officials have not specified the committee's full membership roster, but Netanyahu said Sunday that Manuel Trajtenberg, a professor at Tel Aviv University and the former chief of Israel's National Economic Council, would head the team.

The group will examine reducing taxes, improving access to social services and increasing market competitiveness, Netanyahu said.

They are scheduled to present recommendations to Netanyahu in September.

Lebron James to return to Ohio to bike with students 

Miami Heat star LeBron James is headed back to Ohio this week, this time to lead a 2.6-mile bike ride through Akron’s streets as part of his “Wheels for Education” initiative.

James and 20 high school students will pedal from the University of Akron to East High School where hundreds of students in the program will await them.

The bike ride will be the first event since the program underwent a name change from the King for Kids Bike-A-Thon.

“We felt it was time to change the Bikeathon to something that could be more educational at the same time,” James told the Akron Beacon Journal. “We feel great about it.”