# Useful Abbreviations

Szymon Kopyciński · 23 September 2026



| Abbreviation | Meaning                                        |
| ------------ | ---------------------------------------------- |
| API          | Application Programming Interface              |
| ATM          | At-the-money                                   |
| BBO          | Best Bid and Offer                             |
| CAGR         | Compound Annual Growth Rate                    |
| EMS          | Execution Management System                    |
| ES           | Expected Shortfall                             |
| ETF          | Exchange-Traded Fund                           |
| FIX          | Financial Information eXchange                 |
| FOK          | Fill-Or-Kill                                   |
| FX           | Foreign Exchange                               |
| GTC          | Good-Til-Cancelled                             |
| HFT          | High-Frequency Trading                         |
| IOC          | Immediate-Or-Cancel                            |
| IPO          | Initial Public Offering                        |
| ISIN         | International Securities Identification Number |
| ITM          | In-the-money                                   |
| IV           | Implied Volatility                             |
| L1           | Level 1 Market Data                            |
| L2           | Level 2 Market Data                            |
| L3           | Level 3 Market Data                            |
| LOB          | Limit Order Book                               |
| MBO          | Market-by-Order                                |
| MFT          | Medium-Frequency Trading                       |
| NBBO         | National Best Bid and Offer                    |
| NTP          | Network Time Protocol                          |
| OHLC         | Open, High, Low, Close                         |
| OMS          | Order Management System                        |
| OTC          | Over-the-Counter                               |
| OTM          | Out-of-the-money                               |
| PM           | Portfolio Manager                              |
| PnL          | Profit and Loss                                |
| PTP          | Precision Time Protocol                        |
| QD           | Quantitative Developer                         |
| QR           | Quantitative Researcher                        |
| QT           | Quantitative Trader                            |
| RMS          | Risk Management System                         |
| RTT          | Round-Trip Time                                |
| SWE          | Software Engineer                              |
| TCP          | Transmission Control Protocol                  |
| UDP          | User Datagram Protocol                         |
| VaR          | Value at Risk                                  |


Part of [Glossary Index](/blog/glossary-index) · Previous: [Production Engineering for Trading](/blog/glossary-index/glossary-prod-engineering-for-trading)