Kweku Adoboli, the 31-year-old London man accused of being the rogue trader who cost Swiss banking giant UBS an estimated loss of $2 billion, is a "well-dressed quiet man" of African origin who wasn't the "tidiest" but is very "well spoken," according to a former landlord.

Philip Octave, Adoboli's former landlord, told The Associated Press the UBS employee charged in the rogue trading scheme which has rocked the Swiss bank, possibly causing the entire company a third-quarter loss, that Adoboli fell behind in his rent a couple of times but always paid up in the end.

Octave said Adoboli's rent was $6,320 before the investment banker moved out.

"He was not a party chap," Octave told the AP. "I found no problems."

UBS has not confirmed the name of the trader accused of losing nearly $2 billion in unauthorized trading, but London police said they arrested a 31-year-old man Thursday on suspicion of "fraud by abuse of position" for the UBS rogue trading disaster, and that the man remains in custody.They have confirmed the man charged is Adoboli.

According to a Facebook profile, Adoboli lists UBS as a network, and among "Activities and Interests" lists among many favorites, "Al Jazeera English, Ghana, I'm a Photographer, Not a Terrorist!, Samjhana Moon - Photographer, Wani Olatunde Photography, Brother Mouzone (The Wire), and Vines of Argentina."

Adoboli, from Ghana, lists his home as "London, United Kingdom," and has 417 Facebook "Friends," though the number was 420 early Thursday morning.

Adoboli also lists a London pub, "Boundary - Restaurant, Rooms & Suites, Rooftop."

The Swiss bank's loss "is a staggering demonstration that all the clever systems that the banks now have, especially after the financial crisis, still cannot stop a determined individual getting round them if they want to," Chris Roebuck, Visiting Professor at Cass Business School in London, told Reuters.

Meanwhile, UBS stock took a beating for the news in trading on the Zurich Exchange Thurday, as stock shares dropped as much as 10 percent as markets were stunned with the company's admission that a rogue trader cost the company as much as $2 billion and that the bank will likely post a third quarter net loss after the episode.

And in early U.S. trading Thursday, UBS was down 9.78 percent, or $1.24, to $11.44.

UBS issued a short confessional of the rogue trading loss before European markets opened, explaining to investors that "UBS has discovered a loss due to unauthorized trading by a trader in its investment bank." UBS employes about 18,000 in its investment bank, and most are based outside of Swizterland, working primarily in London and the U.S.

The bank also sent a letter to employees, attempting to calm shaken nerves about the bank's solvency amid the rogue trading loss.

"Although the news is regrettable, the fundamental strengths of the company won't be affected by this," the note said. "We ask that you continue concentrating on your customers. In these uncertain times they are counting on your support."

UBS says no client positions were affected by unauthorized trading, but the blow will be significant -- and some suggest it could threaten the future of UBS' investment bank, already suffering from reputation blows after massive sub-prime losses during the financial crisis resulting in government bailout.

Also, UBS suffered an embarrassing U.S. tax evasion case last year tat exposed Swiss banking secrecy.