The change of approach may be on the advice of auditors and regulators but it is more likely to reflect a desire by UBS's bosses to avoid months of speculation about the bank's exposure, something that Marcel Rohner, the chief executive, described as “distracting”.

主体句式： The change of approach may be… but …

结构分析：这是一个并列句，but 引导的分句比较复杂，to avoid …不定式短语作前面

a desire的定语，而something that…是同位语，该同位语中又包含了一个定语从句。

句子参考译文：

这一做法的改变可能是在审计员或调节员的建议下做出的，但更有可能反映出一种渴望，瑞士联合银行老板们希望避免数月来对该行曝光的猜测，首席执行官马塞尔•罗内尔称其为“转移注意力（的方案）”。