IB API change due to SEC rule

[tsunamilx]

Hi guys,

I received an email from IB saying there will be change in API:

"Due to an external SEC rule update (RIN 3235-AN23), we are required to enforce a change in the round lot sizes of US stock that will vary by price from November 3, 2025. To remove disruption to your trading operations, you must upgrade at a minimum to TWS and TWS API to 10.37 Stable or newer.
If you are already using version 10.37 or above, you may have to ensure that you have ticked the setting “Send market data in lots for US stocks for dual-mode API clients.”
This will ensure you remain informed of the true bid/ask/last sizes."

Does it affect this repo version >= 1.0? Do you have any concerns about this?

I am currently using ib_async 1.0.3, cannot use 2.0.1 as it does not support threads at all.

Thanks.

[gnzsnz]

This seems to be related to #86 I don't think this would require changes, but if you feel it's not the case please share the details

[bobye]

@gnzsnz Just to be clear, if I updated TWS API from 10.35 to 10.37, is there any code changes I need to continue using ib_async (v2+)? Does ib_async support 10.37 out of box?

I am mainly using ib_async for entering orders, I am not very worried about market data API.

[tsunamilx]

Just FYI, TWS and TWS API are different things, TWS API refers to the ibapi package aka the official sdk, I assume we all not using the ibapi package since we are in the repo.

I have TWS version 10.37, and ib_async 1.0.3, I mainly use it for history data and placing orders, it works fine for me.

But I am bit worried about the ib_async being significantly behind of the official ibapi as mentioned in #147 , the official ibapi version number is now more than 200 and ib_async is still on 178.

@gnzsnz do you have a plan to catch up ? or do you think those new changes are not important so not worth the effort, as long as there is no breaking change?

I am worried because next time when IB announce something that would require minimum version of TWS/TWS API thhat ib_async is not compatible with, then we are all screwed.

[gnzsnz]

i'm using 2.0.3 and 1.0.3 on 10.40(latest), I only found #182 (delayed data) on 2.0.3 everything else is working just fine.

There are several things to take into account here. ib_async version 1.0.3/2.0.3, unless you have a specific reason, go for 2.0.3. TWS/ibgateway 10.37(stable) or 10.40(latest). And then the TWS API protocol version, this is negotiated during connection handshake between ib_async and ibgateway, 178 is oldish but functional, over 200 uses protobuf AND legacy API. Only 10.40 can handle that.

ib_async 1.03/2.0.3 both use 178, there are minimal changes in some data objects.

10.40 and 10.37 both support 178. And AFAIK 178 supports #86 "round lot sizes", I have the flag checked and everything works as expected.

[mattsta]

Yeah, so seeing this "new rule" in action, the IBKR communication was very confusing and poorly worded. They implied you should/must enable the checkbox for things to continue working, but if you were already not using lot sizes, you don't need to check the Send market data in lots for US stocks for dual-mode API clients. option at all. The only difference is whether they apply the lot-size multiplier to the bid/ask market data.

So previously a 1 lot bid would show bid x 1 with the "Show market data in lots" enabled and bid x 100 without it enabled since a "lot size" was 100 shares market-wide.

Now since lot sizes are not globally fixed to 100 shares (which was clearly inefficient when we had things like google or amazon with $3,000 share prices pre-split), the lot sizes float with a stock's 2-month-previous average price as:

$0-$250: 100 shares
$250.01-$1,000: 40 shares
$1,000.01-$10,000: 10 shares
Over $10,000.01: 1 share

So if you have "Send market data in lots" enabled for META currently, it will show bid x 1 lot but if you have it disabled, it will show bid x 40 shares.

For example, ASML is operating on a 40 lot size as well, so with "Send market data in lots" disabled (it can be enabled/disabled live too without a gateway restart), you get all depth and quotes in units of 40x:

2025-11-03 09:29:54.893 | INFO     | icli.cmds.quotes.depth:run:171 - ASML :: 3 of 3 :: ASML Grouped by Price :: Row count: 6
2025-11-03 09:29:54.897 | FRAME    | icli.cmds.quotes.depth:run:171 - 
         Bids                                Asks                          
        price size xchanges marketMaker     price size xchanges marketMaker
0    1,063.02   80        1  [DRCTEDGE]  1,063.77   80        1  [DRCTEDGE]
1    1,060.36   80        1      [MEMX]  1,065.86   80        1      [MEMX]
2    1,059.74  320        1       [PSX]  1,066.03  120        1       [PSX]
3    1,020.00   40        1     [EDGEA]  1,105.65   40        1     [EDGEA]
4      988.13   40        1       [BYX]  1,137.54   40        1       [BYX]
sum        -1  560       -1          -1        -1  360       -1          -1
2025-11-03 09:29:54.897 | INFO     | icli.cli:buildAndRun:5878 - [depth] Duration: 2.3584

Also unmentioned (and I don't see this reflected in the IBKR minTick contract data yet for API clients to use), today stocks can now be quoted in $0.005 increments officially (instead of only through HFT) if a stock has an average bid/ask spread of $0.015 or less (basically, if a stock almost always has a bid/ask spread width of $0.01, it can now be quoted in half-penny increments too).

[tsunamilx]

Thanks guys, closing this since nothing needs to be changed.