Sandler O'Neill + Partners, L.P., (Sandler O'Neill) was a full-service investment banking firm and broker-dealer specializing in the financial services sector.
It was headquartered in New York City, and had offices in Boston, Chicago, San Francisco and Atlanta.
The firm also operated a mortgage finance company and registered investment adviser based in Memphis.

Sandler O'Neill provided investment banking services to financial institutions and their investors.
Its services include merger and acquisition advisory, capital markets, fixed income sales and trading, and equity sales and trading, equity research, balance sheet management, mortgage finance, and consulting services.
The firm publishes research on about 300 financial institutions across the United States.

Despite shifts in the way similar Wall Street firms are run, Sandler O'Neill  retained its private partnership structure, and was the largest private investment bank dedicated to the financial sector.
It ranked among the top advisers on bank and thrift mergers as well as in capital raising.

In 2019, the company was acquired by Piper Jaffray and renamed Piper Sandler Companies.
The combined company is headquartered in Minneapolis.
Sandler O'Neill + Partners, L.P., (Sandler O'Neill) was a full-service investment banking firm and broker-dealer specializing in the financial services sector. It was headquartered in New York City, and had offices in Boston, Chicago, San Francisco and Atlanta. The firm also operated a mortgage finance company and registered investment adviser based in Memphis.
Sandler O'Neill provided investment banking services to financial institutions and their investors. Its services include merger and acquisition advisory, capital markets, fixed income sales and trading, and equity sales and trading, equity research, balance sheet management, mortgage finance, and consulting services. The firm publishes research on about 300 financial institutions across the United States. 
Despite shifts in the way similar Wall Street firms are run, Sandler O'Neill  retained its private partnership structure, and was the largest private investment bank dedicated to the financial sector. It ranked among the top advisers on bank and thrift mergers as well as in capital raising.
In 2019, the company was acquired by Piper Jaffray and renamed Piper Sandler Companies. The combined company is headquartered in Minneapolis.
Sandler O'Neill and Partners