Pearson lifted the lid on the deal which saw Turner join Sunderland in August for what was described at the time as an undisclosed fee.
Tigers manager Phil Brown had previously valued Turner at around £12 million but it has been revealed the 25-year-old cost the Wearsiders just £4m. The deal does not include any add-ons based on performances with 33% of the £4m going to Turner's former clubs Brentford and Charlton.
The size of the fee has again raised questions about the necessity to balance the books but Pearson insists the club didn't have to sell, adding: "Under no circumstances was it a financial necessity to sell Michael Turner.
"I can only second guess what people were thinking but there was probably a feeling the player wanted to go and that was the best possible deal available for him.
"It's not incremental, the total amount of cash we will receive for Michael Turner is £2.8m. Those are the facts."
Brentford and Charlton have asked the Premier League to investigate the sale, given Hull's publicised valuation but Pearson is confident the club have done nothing wrong.
He said: "From what I can see, an investigation is unfounded.
"I think the two clubs have seen inflated figures in the press but the only thing we could be accused of is not maximising the fee at the best possible time."