With many TV networks reportedly sold out or near sold out of advertising time in pre- and post-programming around the upcoming Presidential debates, TV advertising revenues among the top TV networks are expected to exceed the total $16 million mark set four years ago.

The top six broadcast and cable TV networks -- ABC, CBS, NBC, CNN, Fox News Channel and MSNBC-- pulled in a collective $15.5 million in national TV advertising revenues for the three Presidential debates, according to iSpot.tv -- yielding more than 410 million impressions.

CNN ($4 million), ABC ($3.3 million), CBS ($2.5 million), and NBC ($2.1 million), Fox News Channel ($2.2 million) and MSNBC ($1.4 million) are the top beneficiaries.

As many as 13 TV networks aired the three 90-minute to 105-minute debates, which ran commercial-free. TV networks sold advertising time in related discussion programming before and after the actual debates.

It is expected this year that as many as 17 to 20 TV networks will air one or more of the Presidential debates.

Top paid-advertisers four years ago for the three debates included Pfizer Columbia Pictures, Adidas, Lionsgate, Warner Bros., Twentieth Century Fox Studios, Jeep, Amazon Prime Video, Oppenheimer Funds, and Vote 4 Energy.

Three Presidential debates between Donald Trump and Hillary Clinton totaled Nielsen-measured viewership of 84 million for the first debate, 66.5 million for the second, and 71.6 million for the third.

The lone 2016 Vice Presidential debate took in $3.7 million in advertising revenue on CBS, ABC, NBC, Fox News Channel, MSNBC and CNN.