It is believed two of its agency group head roles could be at risk, which include positions held by Mike Newcombe, Ben Murphy, Adam Schafer and Caroline Lindford.
A spokesman for Sky confirmed Sky Digital Media is proposing to restructure its sales teams "to drive greater efficiencies in the business".
He added: "This may lead to an overall reduction in headcount, potentially by around 5%, although no decisions have yet been made and a consultation is under way."
The planned redundancies follow the separate departure of Sky Media's deputy managing director, Paul Curtis, in May. He was made redundant as part of a restructure leaving Nick Milligan, the ad sales house's managing director, to take sole charge of the business.
BSkyB's Q1 2009 results showed its ad revenue had fallen 6% year on year from £248m to £234m over the nine months to 31 March, reflecting, it said, a "weak advertising environment".
However, BSkyB's total revenue was just under £4bn over the nine months to 31 March, with its subscription revenue accounting for the majority of its income.