CNBC's Eamon Javers has the latest details on a ricin-laced letter sent to Sen. Wicker's office. And, Clark Ervin, former Homeland Security Department official; and Clint Van Zandt, former FBI profiler, discuss whether Monday's bombing leaves major events such as sporting, more vulnerable to future attacks.

Scott Kessler, IT group director and senior equity analyst at S&P Capital IQ, says that Yahoo's balance sheet assets are what will drive the stock in the coming quarters and not its potential turnaround

Steve Bertoni, Forbes associate editor; and Rebecca Patterson, Bessemer Trust, share their investment strategies after gold's big dip; "squishy" earnings and possible downgrades in France and/or Germany.

CNBC's Scott Cohn reports the type of devices used in Monday's bombing in Boston are beginning to emerge.

Bomb fragments are being reconstructed at an FBI laboratory, reports CNBC's Scott Cohn. And, Philip Mudd, New America Foundation, discusses the psychological impact of terrorism and how to avoid copycat attacks.

Michael Ward, President, Chairman, & CEO of CSX Corporation, discusses his company's better-than-expected earnings, and weighs in on the outlook on the economy.

Jason Toussaint, World Gold Trust Services CEO, explains why there are still plenty of reasons to be bullish on gold bullion.

Chris Rolland, FBR Capital Markets analyst, takes a look at Intel's penny earnings miss on revenues of $12.6 billion, and discusses the shift away from the PC market.

Anthony DiClemente, Barclays analyst, breaks down the tech giant's quarterly numbers and weighs in on CEO Mayer's turnaround plan.

Matthew Turner, Macquarie Securities; and Kevin Book, ClearView Energy Partners, discuss how to trade commodities after the sell-off in gold and oil.

CNBC's Kelly Evans reports European markets were dragged lower by miners in morning trading.

A ricin-tainted envelope was sent to the Capitol Hill office of Sen. Roger Wicker, (R-MI), reports CNBC's Eamon Javers.

Maya Bhandari, director of global macro strategy at Citi, discusses the potential interest rate increase from the Brazilian central bank but says Brazil should have allowed its currency to strengthen.

CNBC reports on Margaret Thatcher's funeral as her coffin arrives at St. Paul's Cathedral, where over 2,000 guests will bid her farewell.

Brian Reynolds, chief market strategist at Rosenblatt Securities, says gold prices are likely to fall further for a couple weeks before stabilising which will prompt a structuring of commodities.

Rahul Sharma, managing director at Neev Capital, tells CNBC he is positively surprised by Burberry's results and says the market should stop focusing so much on the Chinese luxury consumption and look into emerging markets.

Paul McNamara, investment director at GAM, explains that the Chinese government has a lot more scope to deal with economic troubles and that a full-scale crisis in the country is highly unlikely.

Mark Gettleson, political analyst at PoliticsHome.com, tells CNBC that Margaret Thatcher changed British politics to be less about identity and more about ideas.

Brian Weiser, Senior Research Analyst at Pivotal Research Group, talks to us about the market's reaction to Yahoo's earnings report, and tells us how we should trade the results.

Adrian Foster, Head of Financial Markets Research, Asia Pacific at Rabobank tells CNBC's Cash Flow why he's not concerned about the impact of the ZEW survey on his forex trades.