How to connect IPOs/M&A deals with firms involved

For a given IPO, merger, or acquisition how/where can I find the names of the firms/banks underwriting the IPO or managing the merger/acquisition? (e.g. Who is underwriting Dropbox?)

And conversely, for a given firm, how can I find out the IPOs, mergers, and acquisitions in which it has been (recently) involved? (e.g. what IPOs/deals has Morgan Stanley managed?)

Sometimes an article covering a given IPO, merger, or acquisition provides the names of firms involved, but generally I have trouble finding this information. Thanks, in advance, for any help!