The Leverkusen-based group's stock gained 7.8 percent to trade at 67.90 euros ($75.96) by 10:30 am in Frankfurt (0830 GMT), topping the blue-chip DAX index.

Bloomberg News had earlier reported Bayer could pay out as much as $8 billion in a settlement with more than 18,000 US plaintiffs, who allege the weedkiller Roundup caused their cancer.

On Wednesday, German business magazine Wirtschaftswoche reported that hearings in two such cases may be delayed, stoking speculation that an out-of-court agreement could be on the cards.

A Bayer spokesman told AFP the group "does not comment on rumours", referring back to its second-quarter earnings statement, which vowed both energetic defences in lawsuits and engagement in a court-ordered mediation process in California.

"We believe that we will ultimately prevail in this litigation on the strength of sound science," chief executive Werner Baumann told investors in a July 30 telephone conference.

An $8 billion settlement would be well below estimates from analysts, who predict the legal tangle could end up costing well over 10 billion euros.

After its mammoth takeover of US seeds and pesticides maker Monsanto for $63 billion last year, Bayer has been battered with a wave of lawsuits over the flagship herbicide, based on its active ingredient glyphosate.

Juries in several lower courts granted plaintiffs massive damages awards, although they were later reduced by judges and Bayer vowed to appeal -- saying the weight of scientific evidence is against glyphosate causing cancer when used appropriately.

Plaintiffs' lawyers have often argued based on a 2015 finding by World Health Organization arm IARC that classed glyphosate as "probably carcinogenic".

But this was a finding in absolute terms, rather than one related to typical levels of exposure.

Bayer points to long-term studies of thousands of glyphosate users which it says show no increased cancer risk.