Sue Ann Hamm, the ex-wife of Oklahoma oil tycoon Harold Hamm, was awarded over $1 billion in cash and assets during their divorce trial last week. However, it seems Sue Ann is not happy with the ruling and will be appealing the judgment on the grounds that it “grossly undervalues” the money she is entitled to, especially after working in the company during her marriage with Hamm. The ruling allowed Hamm to keep an estimated 94 percent of the rise in his shares during their marriage.

“Sue Ann is disappointed in the outcome of this case. She dedicated 25 years as Harold’s faithful partner in family and business,” said Sue Ann’s attorney Ron Barber. According to a court filing, Judge Howard Haralson ruled that Hamm should pay Sue Ann a total of $995.5 million dollars with about a third of the money to be paid for by the end of the year. She was also awarded additional assets including a ranch and a house, both located in Oklahoma. The assets are said to be worth millions.

Oil baron has to pay ex-wife nearly $1 billion — and he’s thrilled http://t.co/rmCShN5SN0 pic.twitter.com/w2GKKIj3Fv

— Business Insider (@businessinsider) November 11, 2014

The divorce settlement that was reached on Monday, November 10, is considered as one of the biggest settlements in US history. Hamm is the CEO of Continental Resources, one of the largest oil companies in the United States. Hamm also owns 68% of Continental Resources’ stock, which is worth $13.5 billion.

Sue Ann is a lawyer and economist who has worked in key positions at Continental Resources during their 26 years of marriage. According to court documents, Sue Ann also led the crude marketing department at one point.

In a court filing from 2013, Sue Ann revealed that Harold was having an affair, which prompted her to file for divorce. The couple got married back in 1988 and they have two daughters together. It is worth noting that Harold and Sue Ann never signed a prenuptial agreement when they got married.