Barbara Borden, the co-chair of Cooley's global M&A practice, advised on acquisitions worth more than $7 billion last year while leading her group on more than 200 deals.

The No. 1 issue that keeps me and my clients up at night is …

I am usually kept up by specific deals that have thorny issues that need to be resolved. I think a lot of our clients are nagged by the need to sustain short-term results because of market expectations rather than managing for longer-term success.