MADRID (Reuters) - Spanish utility Iberdrola (>> Iberdrola) used its influence to change the management of Siemens Gamesa (>> Siemens Gamesa Renewable Energy) on Friday after the wind-power joint venture suffered two profit warnings in less than three months.

Germany's Siemens (>> Siemens) has a controlling stake of 59 per cent in Spanish-based Siemens Gamesa but Iberdrola, with an 8 percent stake, has a say in some governance matters thanks to a deal signed when Siemens Wind agreed to merge with Gamesa last year.

Iberdrola demanded change at a board meeting on Friday, people with knowledge of the situation said, prompted by a second profit warning from the joint venture last week.

Siemens Gamesa, which vies with Denmark's Vestas as the world's biggest wind turbine maker, announced a management reshuffle shortly after the board meeting.

The changes include a new chief financial officer and new CEO for the rapidly growing offshore division. Miguel Angel Lopez will replace Andrew Hall after only six months as CFO.

Iberdrola, Siemens and Siemens Gamesa declined to comment on the changes.

Siemens Gamesa is also delaying to February the Capital Markets Day where it was going to announce a new strategy.

CULTURE CLASH

The clash at the joint venture highlights the problems that can emerge when former cross-border rivals with contrasting business cultures merge and establish new chains of command.

"The relationship with Iberdrola had been difficult from day one", one of the sources said.

"Siemens Gamesa is now a German elephant. Every single important decision must be approved by the Germans. It has lost Gamesa's agility," said another source.

Since the merger Gamesa Siemens' shares have tumbled more than 44 per cent as it repeatedly cut its forecasts for profitability. On Friday, its shares hit the bottom of the Stoxx 600 index <.STOXX> losing 4 percent.

The wider industry has suffered from stiff competition and a winding down of state subsidies, but Danish rival Vesta's  (>> Vestas Wind Systems) shares have fallen by just 4.9 percent during the same period.

One reason for Siemens Gamesa's underperformance is its exposure to the Indian market, which is in transition from a subsidised market to an auction-led one leading to more competition and pressure on wind turbine prices.

"The shift in the Indian wind market to an auction system has resulted in a significant slowdown in installations in 2017 ... partially affecting Siemens Gamesa’s 2017 earnings", said Goldman Sachs in a recent report.

Meanwhile, Siemens has announced another joint venture with French Alstom to create a European champion in the railway sector.

(Additional reporting by Alexander Huebner in Munich; Editing by Tom Pfeiffer and Elaine Hardcastle)

By Jose Elías Rodríguez and Andrés González