Black slaves were owned by both blacks and whites. This subject however is admittedly one of the more difficult to define. Percentages vary depending on source. I will attempt to give some numbers on the number of owners but the real truth point that is important here is that 100% of people in the colonies did not own slaves although everyone today, including relatively new immigrants are held accountable for slavery.
Slaves were expensive. This limited who could own one or more. The rich then are as the rich now, a small percentage of the people. The purchase price was not the only prohibitive factor. There are other factors that are but not limited to: room, board, clothing, medical, task masters, bounty hunters, confinement devices, tutor(s) and tax(s). This is quite a financial undertaking to which many were ill-equipped. Overall 1.25 – 8% (8% from the liberal and often misinformed wiki) owned slaves (white and black). Interestingly, up to 14% of free blacks owned slaves. Yes there were benevolent owners but there were also people like William Ellison who owned 63 slaves for exploitation and was in the in the top ten percent of the richest people in South Carolina.
Again, what is notable is that more free blacks owned slaves than whites and at the highest estimated percentage not all whites owned blacks, yet all whites including 20th century immigrants are held accountable for slavery. This is reprehensible. Regardless of any evidence on either side the indisputable fact that always becomes camouflaged by this unjustified emotional issue is the fact that no one alive today was ever a slave nor slave owner in the United States (defined by the subject at hand). This effectively renders all arguments regarding blame, reparations, and others issues moot.