Bolton have signed Portsmouth defender Andy O'Brien on a two-year contract for an undisclosed fee.
O'Brien spent two seasons at Fratton Park
The 29-year-old Republic of Ireland international is Trotters boss Sammy Lee's 12th signing of the summer.
"Andy is an astute acquisition. He will give us greater strength in depth and options in critical areas," Lee told the Bolton website.
O'Brien, who spent two seasons at Fratton Park, will be in the squad for Wednesday's game against Fulham.
He was not included in the Portsmouth team which drew 2-2 with Derby on the first day of the season and had not played for Harry Redknapp's side since 1 April.