By Tim McLaughlin BOSTON (Reuters) – Mutual funds run by Fidelity Investments bought a modest 2.4 million shares of Twitter Inc in the days after its public debut, revealing that they were not willing to take any early, big bets on the microblogging site. Fidelitys Contrafund led the way, holding 1.1 million shares at the end of November, according to the latest available fund disclosures. In contrast, Contrafunds stake in Facebook Inc was worth $1.6 billion at the end of November. Some analysts say Twitter may lose out to Facebook and Google Inc in the battle for online ad revenue.