Mistakes of judgement overshadowed her second mandate with the European Commission, such as the unsuccessful appointment of a US economics professor as Chief Economist for competition.

[7][8] Despite these setbacks, her aggressive antitrust enforcement against Big Tech culminated in a 2024 European Court of Justice victory that upheld landmark tax rulings against Apple and Google, decisions widely viewed as sealing her legacy as a steadfast regulator and vindicating her potent EU trustbuster campaign.

[9][10][11][12][13] In her capacity as Commissioner for Competition, Vestager has gained international recognition for investigating, fining, or bringing lawsuits against major multinational companies including Google,[14] Apple Inc.,[15] Amazon,[16] Facebook, Qualcomm,[17] Siemens, Alstom,[18] and Gazprom.

[17] Vestager has been the target of criticism by American corporations and US President Donald Trump for her efforts throughout her tenure as European Commissioner for Competition.

[citation needed] On 15 June 2007 Vestager secured election as her Party's parliamentary group leader in the Folketing, replacing Marianne Jelved.

[24] When Denmark's Prime Minister Lars Løkke Rasmussen called an early election in 2011 after failing to secure majority lawmaker backing for his economic stimulus package, Vestager's Social Liberals and the Conservative People's Party formed a political alliance, pledging to work together no matter which political bloc would win the election.

Having forced through deep cuts in unemployment benefits of Denmark's generous social welfare system after the country's economy narrowly escaped recession in 2012,[27] she was at one point considered by Danish media and pollsters as the most powerful person in government, even above Thorning-Schmidt.

[31] Between 2011 and 2014, Vestager led Denmark's campaign against Basel III liquidity rules, arguing in favor of allowing banks to use 75 percent more in covered bonds to fill liquidity buffers than allowed under Basel III rules; at the time Denmark's $550 billion mortgage-backed covered bond market, part of the country's two-century-old mortgage system,[32] was the world's largest per capita.

[33] In 2013 she ruled out slowing down steps toward stricter requirements for systemically important lenders and reiterated her stance that banks won't get tax breaks to help them through the transition caused by regulatory reform.

You don’t have influence or produce results if you’re standing on the sideline.”[36] On 31 August 2014, Prime Minister Thorning-Schmidt nominated Vestager as Denmark's EU Commissioner in the Juncker Commission.

[39][40] In her confirmation hearings, Vestager said she favored settlement of cases before they come to a final executive judgment, for reduced fines or negotiated concessions from the companies.

[20] In 2014, she launched proceedings against Gazprom, one of Europe's main gas suppliers, over allegations of breaching EU antitrust rules by putting in place artificial barriers to trade with eight European countries: Estonia, Latvia, Lithuania, Poland, Czech Republic, Slovakia, Hungary and Bulgaria.

[49] In July 2018, she fined Alphabet (Google) €4.3 billion for entrenching its dominance in internet search by illegally tying together their service and other mobile apps with Android.

[5] Vestager’s campaign for the presidency of the European Commission encountered resistance in France, following her decision to veto the merger between Alstom and Siemens.

[60][61] On the same day, the French President Emmanuel Macron expressed his concerns regarding the choice of Scott Morton and his surprise that no qualified candidates could be found in Europe.

Following the resignation of Thierry Breton in September 2024, Vestager assumed his portfolio as Commissioner for Internal Market, and other related responsibilities, until the end of the current Commission mandate.

[68][69] In 2015, as the European Commissioner for Competition, Margrethe Vestager opposed the intervention of the Italian FITD (Inter-Bank Deposit Protection Fund) to support the capital increase of Banca Tercas, which had been approved by the Bank of Italy, defining it as an anti-competition state aid.