Charlton and Coventry fans threw hundreds of plastic pigs on the pitch in a joint protest that interrupted Saturday's match at The Valley.
The supporters were protesting against the two League One clubs' respective owners, and had also organised a joint march to the stadium before the game.
Play was delayed for about five minutes while the pigs were cleared.
Charlton went on to win the match 3-0, meaning Coventry remain bottom.
Fans of the London side have made repeated protests against owner Roland Duchatelet's running of the club.