One of the devices was left outside Schwab's mansion overlooking the world famous Pebble Beach golf course, 200 km south of San Francisco, while the other was at his offices in the nearby town of Carmel.
The briefcases, which had suspicious wires sticking out, were discovered on Monday. X-rays showed that they were probably bombs, and explosives experts were called to detonate them.
"There was explosive material" in both parcels, a spokeswoman for the Monterey County Sheriff's said, declining however to say whether the devices were set to explode or what kind or quantity of explosives were in them.
No injuries or damage was reported in connection with the bomb, and Schwab was not in the resort town at the time, according to a spokesperson. The Federal Bureau of Investigation (FBI) is assisting in investigating the case.
Schwab is founder and chairman of San Francisco-based Charles Schwab and Co, which pioneered discount retail stock broking beginning in the 1970s and grew to become the country's fourth largest stockbroker.
"I understand they were not armed devices, and we consider them to be a hoax. But we are treating it extremely seriously"
Battered by the fall of US stock-markets, Schwab has cut the company's workforce by nearly 10,000 jobs since late 2000. Last week the company announced it would lay off 250 more employees and shut down a number of offices around the country.
Spokesperson Sarah Bulgatz said Schwab, whose net worth is estimated at $2.7 billion, had not received any threats prior to the incident.
"I understand they were not armed devices, and we consider them to be a hoax," said Bulgatz. "But we are treating it extremely seriously."