An exchange operates a marketplace where orders interact. A market participant identifier, or MPID, identifies a firm participating in the market. A routing label identifies an execution destination or service. An algorithm controls how an order is worked.
This guide covers the exchanges, firms, and routing labels traders may encounter in U.S. trading platforms, including thinkorswim. Labels vary by platform, and older names sometimes remain visible after a business changes its name or ownership. Schwab describes its Level II columns as identifying either a marketplace or a market maker.
Stock exchanges and exchange labels
1. New York Stock Exchange — NYSE
The NYSE is a stock-listing and trading exchange that combines electronic trading with a physical trading floor. Designated market makers support its listed securities, and its opening and closing auctions bring together orders at the start and end of the trading day.
2. NYSE Arca — ARCA / ARCX
NYSE Arca is an electronic exchange for stocks and exchange-traded products, including ETFs. ARCA is a familiar platform label, while ARCX is its market identifier code. Arca also has an options market; the meaning of a displayed label depends on the instrument being traded.
3. NYSE American — AMEX
NYSE American is the successor name to the American Stock Exchange and NYSE MKT. Its equity market focuses on smaller companies and uses electronic designated market makers. NYSE American Options is its options marketplace.
4. NYSE National
NYSE National is a separate electronic equities exchange within NYSE Group. It provides another market on which listed stocks can trade; it is distinct from the main NYSE exchange.
5. NYSE Texas — Formerly Chicago Stock Exchange / NYSE Chicago
The former Chicago Stock Exchange became NYSE Chicago and subsequently NYSE Texas. NYSE Texas launched in 2025 as an electronic equities exchange based in Dallas. Older CHX labels should be understood in that historical context, rather than described as a separate modern exchange.
6. Nasdaq — NSDQ / NASDAQ
Nasdaq is a stock-listing and electronic trading exchange. NSDQ commonly appears as a platform label for Nasdaq. An exchange label identifies the marketplace, not necessarily the individual firm behind an order.
7. Nasdaq Texas — Formerly Nasdaq BX / Boston Stock Exchange
Boston Stock Exchange became Nasdaq BX, which changed its name to Nasdaq Texas in February 2026. Older platforms or documents may still use BX, NQBX, or BSE references. Nasdaq Texas and NYSE Texas are separate exchanges operated by different groups.
8. Cboe BZX — BATS / BZX
Cboe BZX is one of Cboe’s U.S. equities exchanges. BATS is a legacy name associated with the exchange and its former parent company. “BATS Global Markets” should not be treated as an additional exchange alongside BZX.
9. Cboe BYX — BYX / BATS Y-Exchange
Cboe BYX is another U.S. equities exchange within Cboe. Thinkorswim’s stock-code documentation maps Y to BATS Y-Exchange. It should not be called “NYSE Y Exchange.”
10. Cboe EDGA — EDGA
Cboe EDGA is an electronic equities exchange descended from Direct Edge. Although older descriptions may call it an ECN, its current classification is a national securities exchange.
11. Cboe EDGX — EDGX
Cboe EDGX is a separate electronic equities exchange within Cboe. EDGA and EDGX have different order books and trading rules. Cboe also operates EDGX Options, so readers should distinguish the stock and options contexts.
Cboe operates four U.S. equities exchanges: BZX, BYX, EDGA, and EDGX. Fees and rebates depend on the exchange’s current schedule and the order involved; none should simply be described as universally “low cost.”
12. Investors Exchange — IEX
IEX is an electronic stock exchange known for its 350-microsecond incoming-order “speed bump.” The delay supports exchange features designed to reduce disadvantages caused by very small differences in the timing of market information. It does not exclude market makers or high-frequency trading firms.
13. MEMX
MEMX operates an electronic equities market using price/time priority. Its group also operates options markets. A MEMX reference should therefore be interpreted in the context of the product and platform.
14. MIAX Pearl Equities
MIAX Pearl Equities is a fully electronic U.S. stock-trading venue. It is distinct from the options markets operated by MIAX.
15. Nasdaq PHLX — PHLX
Nasdaq PHLX operates an options marketplace combining electronic and floor-based trading. For equities, Nasdaq’s PSX market is a separate trading platform associated with PHLX. A PHLX label should therefore be interpreted with the security type in mind, rather than automatically described as an options quote.
Other exchanges
This is a guide to commonly encountered labels, not a complete directory of every U.S. exchange. Additional registered exchanges include the Long-Term Stock Exchange, 24X National Exchange, Green Impact Exchange, and Texas Stock Exchange. Options markets also include BOX, Cboe C2, Nasdaq ISE, Nasdaq GEMX, Nasdaq MRX, and several MIAX venues.
The SEC maintains an official exchange directory. Registration alone does not mean that an exchange is available through every broker.
Market makers and brokerage-firm identifiers
The following codes identify firms rather than standalone stock exchanges. A firm can have multiple identifiers, and a quote can represent its own trading activity or orders handled for clients.
Established firm codes
| Code | Firm | What the label identifies |
|---|---|---|
| ETMM | G1 Execution Services | A market-making and execution firm. |
| GSCO | Goldman Sachs & Co. | A Goldman Sachs broker-dealer identifier. |
| IMCC | IMC Financial Markets | A trading-firm identifier, not a clearing corporation. |
| VIRT | Virtu Americas | A Virtu trading and execution entity. |
| SGAS | SG Americas Securities | A Société Générale securities entity. |
| MSCO | Morgan Stanley & Co. | A Morgan Stanley broker-dealer identifier. |
| CDRG | Citadel Securities | A Citadel Securities market-participant identifier. |
| TSSM | Two Sigma Securities | A Two Sigma identifier, not TradeStation Securities. |
| CANT | Cantor Fitzgerald & Co. | A Cantor Fitzgerald trading identifier. |
| INTL | StoneX Financial | A StoneX identifier associated with the former INTL naming. |
| NEED | Needham & Company | A securities brokerage and trading identifier. |
| KEYB | KeyBanc Capital Markets | A KeyBanc securities-trading identifier. |
| UBSS | UBS Securities | A UBS securities-trading identifier. |
These mappings identify the registered participant; they do not establish execution quality, quote size, or the identity of an underlying client.
Additional codes and commonly misidentified firms
| Code | Correct firm |
|---|---|
| ADAM | Canaccord Genuity |
| BARD | Robert W. Baird & Co. |
| JSSF | Citizens JMP Securities |
| LEHM | Barclays Capital Inc./Le, as recorded in Nasdaq’s directory |
| SOHO | Two Sigma Securities |
| WBPX | Summit Securities Group |
| WCHV | Wells Fargo Securities |
| WBLR | William Blair |
| SSUS | Susquehanna Securities |
| RBCD | RBC Capital Markets Corporation, as recorded in Nasdaq’s directory |
| XGWD | Latour Trading |
| FLTG | Flow Traders U.S. |
These replace several misleading expansions sometimes attached to the codes. For example, BARD does not mean Barclays Direct Execution, WBLR does not mean Whitebox Advisors, and WCHV does not mean WealthBridge Capital. LEHM should not be described as today’s independent Lehman Brothers business.
Among the additional participants, Flow Traders provides liquidity on exchanges and directly to institutional counterparties. Two Sigma Securities uses systematic trading and market-making strategies. Latour Trading is included among NYSE’s proprietary supplemental liquidity providers. These are firms participating in markets, rather than exchanges themselves.
Historical names and platform-specific labels
CHXE
Schwab’s exchange-code guide includes CHXE and maps it to M in the stock column. The guide does not establish a separate exchange called “CHX Enhanced.” Treat CHXE as a platform label requiring context, particularly given the Chicago exchange’s subsequent name changes.
OTCBB — OTC Bulletin Board
OTCBB was a FINRA-operated quotation system, not a stock exchange. FINRA discontinued it on November 8, 2021. It should not be presented as an operating venue or as a current listing tier.
CSFB — Credit Suisse First Boston
CSFB is a historical Credit Suisse First Boston abbreviation. It belongs in a discussion of legacy names rather than a list of current standalone stock exchanges. Any current routing label using those letters needs confirmation from the platform.
G1X — G1 Execution Services
TradeStation documentation uses G1X for a route to G1 Execution Services. It is an execution-service destination, not a stock exchange. Availability and order handling depend on the broker and its current routing configuration.
Knight Link
Knight Link is a named execution route associated with Knight’s internal liquidity. TradeStation’s documentation describes it as interacting with that liquidity and canceling any unfilled remainder rather than forwarding that remainder elsewhere. Because this is a legacy route name, current availability should be checked with the broker.
MF/MM — Sometimes written as MFMM
Schwab’s thinkorswim exchange-code table lists MF/MM under stocks and maps it to F. However, that table does not explain the abbreviation or identify a specific firm behind it. It should be presented as a documented platform label with an unresolved definition, rather than assigned a speculative company name.
H
Do not automatically identify H as Citadel Securities. In Schwab’s published options-code table, H means ISE Gemini, now Nasdaq GEMX. Single-letter codes depend on the platform and instrument.
SSC
SSC remains unverified in this guide. Without the originating platform’s documentation, it should not be assigned a firm name or described as a stock exchange.
Execution algorithms
Algorithms describe how an order is executed. They may use multiple venues and should be listed separately from exchanges and market makers.
POV-ALGO — Percentage of Volume
A participation algorithm that aims to trade at a specified percentage of market volume. Its execution pace generally increases when market activity rises and decreases when activity falls.
TWAP-ALGO — Time-Weighted Average Price
An algorithm that spreads execution across a chosen time period. It generally aims for a relatively even trading pace, subject to its settings, price constraints, and available liquidity.
VWAP-ALGO — Volume-Weighted Average Price
An algorithm that schedules execution around a volume profile, seeking a result near the relevant volume-weighted average price benchmark. It does not guarantee that price or completion of the order.
Sweep-ALGO
TradeStation describes Sweep-ALGO as seeking prompt execution by accessing liquidity across multiple exchanges or market centers simultaneously. Its emphasis is on finding available liquidity quickly.
SweepPI-ALGO
TradeStation describes SweepPI-ALGO as seeking price improvement while limiting market impact and slippage. Unlike an immediate sweep, it may allow an order to rest at a price level while seeking a better execution opportunity.
Reading the codes correctly
A Level II label tells you which marketplace or participant is associated with a displayed quote. It does not necessarily reveal the ultimate investor behind the order, the participant’s complete position, or whether the displayed size represents all available liquidity.
Open a Level II window or an order-routing menu and you’ll see names like ARCA, EDGX, GSCO, and SOHO. These labels help identify where quotes originate or how an order may be handled—but they don’t all represent stock exchanges.
Likewise, seeing a venue in market data does not establish that your broker lets you route directly to it. Check the platform’s order-entry documentation separately from its market-data labels.