The move would further expand the UK addressable TV advertising market. The two have been in on-off talks for several years.
Any deal could also include the third party channels represented by Channel 4’s sales house, including BT Sport and UKTV.
AdSmart, which enables different ads to be shown to households watching the same programme, is currently available to 30 million viewers following the inclusion of Virgin Media in July.
Last September, Sky and Channel 4 agreed to share coverage of the British Grand Prix, while drama Tin Star received a Channel 4 screening, and selected Channel 4 and Walter Presents drama series were released on the Sky and NOW TV platforms.
Sky AdSmart declined to comment.