About 4:30 p.m., the 12-member jury sent U.S. District Judge David Hittner a note admitting it could not reach a unanimous guilty verdict on all of the 14 counts against the former financier.
Whether that means they've reached verdicts on some of the charges wasn't clear.
They'll resume deliberations at 9:30 a.m. today.
Stanford, 62, stands accused of masterminding a $7.2 billion Ponzi scheme on purchasers of certificates of deposit through his Stanford International Bank in Antigua.
When he and his attorneys read the jury note about a deadlock, courtroom reports said Stanford took off his glasses, looked upward and closed his eyes as if in prayer. Then, he nodded to family members.
Twenty-two-thousand investors worldwide claim they lost their life savings when the Stanford empire collapsed in 2009 under the weight of U.S. Securities and Exchange Commission investigation.
More than a thousand Mississippians call themselves Stanford's victims. The company had offices in Tupelo, Jackson and Memphis.
Stanford insists he could have saved his financially floundering company if assets hadn't been frozen by an SEC lawsuit.
Stanford is accused of mail and wire fraud, obstruction of a federal investigation and conspiracies to commit mail and wire fraud, to launder money and to obstruct a federal investigation.
If convicted, he faces decades in federal prison and millions in fines, as well as forfeitures of funds in dozens of bank accounts.
The Houston Chronicle reported the jury has been at work about 23 hours since it began work late Thursday. It must be unanimous on each count to vote for conviction.
Stanford's trial began Jan. 21 in Houston, where he built his financial services enterprise. Lawsuits against Stanford by alleged victims are on hold until completion of the criminal case and action by a court-appointed receiver in Dallas.
A separate trial set for September will push similar criminal charges against King and three former Stanford executives, including Baldwyn native Laura Pendergest-Holt.