Mercader started working for CBS News in 1987 as a page in the company's page program, then began her news career at CBS Newspath, where she produced pieces for distribution at CBS' affiliates. She also worked on the network's foreign and national news desks, helping to produce breaking news pieces on the death of Princess Diana and the September 11 attacks. In 2004, Mercader won an Emmy Award for Business and Financial Reporting for helping to produce "The Little Engine That Could, Spam" a "CBS News Sunday Morning" feature report on computer spam.