Utilize the input text as a context reference, choose the right relationship between Janet Yellen and President from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

Investors will look for clues on the timing of a rate hike when Fed Chair Janet Yellen and St. Louis Fed President James Bullard speak at a conference in St. Louis later on Wednesday.

Answer: position_held