A tiny Wall Street firm advising Pfizer on its giant deal has had an incredible year

It has been a good year for Guggenheim Securities.

The 16-year-old firm has been an adviser on five massive transactions in what has been one of the busiest years for mergers and acquisitions on record.

Its biggest deal yet, Pfizer's $160 billion deal with Allergan, was announced Monday.

Guggenheim Securities is one of three boutiques advising Pfizer on the inversion deal.

The others are Moelis & Company and Centerview Partners. Goldman Sachs is also advising Pfizer on the deal.

As the investment bank has expanded further into sectors that Wall Street's biggest banks count on for M&A revenue, it has also taken key talent from top advisers elsewhere in the investment-banking business.

This includes Fares Noujaim, who was a star banker under Guggenheim executive chairman Alan Schwartz when they both worked at Bear Stearns, as well as healthcare-sector veterans from JPMorgan and Bank of America Merrill Lynch: Jeff Hoffman and Joseph Kohls.

Here is a breakdown of the 10 biggest deals for the bank, as tracked by the M&A data provider Dealogic - many of them, from the past 12 months - that have increased Guggenheim's clout in the banking world.