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Jessica Simpson's fashion line celebrated its 10th anniversary this week, and the business mogul, whose company is valued at over $1 billion, sat down with CNBC's 'Closing Bell" on Sept. 10 where the revealed the worst financial decision she's made might have been getting married to Nick Lachey.

When host Kelly Evans asked Simpson to name one of worst professional mistakes of her life, Simpson laughingly replied, "Biggest money mistakes? I don't know. For some reason I thought of my first marriage!"

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Simpson, who is now married to former NFL star Eric Johnson, tied the knot with Lachey in October 2002. The couple announced they were separating in November 2005, and Simpson filed for divorce the next month.

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During their time together, Simpson and Lachey starred in the MTV reality show "Newlyweds: Nick and Jessica," which chronicled aspects of their marriage.

Simpson and Johnson, who share 3-year-old daughter Maxwell and 2-year-old son Ace -- got engaged in 2010 and tied the knot in July 2014.

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After divorcing, Lachey moved on and wound up exchanging vows with actress Vanessa Minnillo in 2011, which whom he had two children -- 2-year-old son Camden and infant daughter Brooklyn.

Meanwhile, "Closing Bell" Kelly Evans told Simpson, " "That's actually a common answer, believe it or not." After all, divorce can be quite expensive.