LONDON: The Oprah Winfrey Show is to close in 2011 after more than two decades on air, the production company behind the programme has said. Billionaire Winfrey, one of the most influential women in the US, has hosted the show since 1986. A spokesman for the star’s Harpo production company would not say why she had made the decision, but said she would discuss it in the show of November 20. Winfrey is expected to focus instead on the launch of her own TV channel. OWN, the Oprah Winfrey Network, is scheduled for launch in 2011. The Oprah Winfrey Show is a media institution in the US, with an average of seven million viewers. Authors appearing on the show often become bestsellers overnight and Winfrey’s support for US President Barack Obama was seen as crucial to his campaign. Oprah is still the highest-rated talk show on US television but audiences are half of what they were a decade ago.