AOL was recently relaunched as a free portal, and both AOL and MSN have seen a decline in dial-up subscribers.
Julian Smith, European online advertising analyst at Jupiter Research, said: "It appears that both are struggling against the likes of Yahoo and Google, so this is perhaps a logical defensive action which could boost advertiser numbers by combining the subscriber base."
The move comes soon after MSN launched an advertising option similar to Google's AdWords in a bid to catch up with the model created by the search giant.
Other analysts speculate that links between the two could increase the probability of a closer merging of their instant messaging platforms.
"Communications such as instant messaging and VoIP are becoming increasingly important, so that will be a target as well," said Smith.
Kicking Palantir off of AWS is among their demands, too
Rafaela Vasquez was watching The Voice at the time of the crash, new evidence shows
PUBG price slashed on Steam after selling more than 50 million copies - as daily player numbers plunge
Use the same password for every website? It might be time to change them all