Louise Lucas brings to six the number of journalists working under Lex editor George Graham.
Lucas has been a page editor on the FT's Companies & Markets section since 1999. She joined the paper in 1993 and spent her first six years as a correspondent in Hong Kong. Her knowledge of Asian companies is expected to be useful in her new role, a spokesman said.
Lex appears daily on the back page of the FT and online at FT.com.
Items on companies or sectors are posted on the Lex Live section of the website by 1pm each day, in time for the start of trading in New York.
There are three items each day in the print version, which may be different to the online stories.
Articles from the Lex team can also vary across the FT's UK, European and US editions.
Lex writer Neil Buckley left the column earlier this year to become the FT's consumer industries correspondent, based in the US.