Why is timezone eastern time (05:00:00Z)

Alpaca Market Data
1

I’m located in the west coast. I just did an API call to the historical bars.

url = ‘https://data.alpaca.markets/v2/stocks/bars?symbols=AAPL&timeframe=1Day&start=2017-09-01’

And one the latest entry has this information.

{
“c”: 249.79,
“h”: 252,
“l”: 247.0949,
“n”: 532898,
“o”: 247.5,
“t”: “2024-12-19T05:00:00Z”,
“v”: 60882366,
“vw”: 249.866349
}

My question - why is the timezone eastern time? Shouldn’t it be UTC or even timezone aware (I’m in PST). Is there another parameter I should pass in the URL?

2

I guess my follow up question, if it is indeed UTC, converting it to PST, it will be 12/18, but it is showing me 12/19 data for Apple.

3

Hi :wave:

why is the timezone eastern time?

The daily bars’ starting timestamp is midnight in New York. The reason for this is that the exchanges are located there.

Shouldn’t it be UTC

No. If it was UTC midnight, the last hour of extended hour trading (19-20 ET = 00-01 UTC) would be part of the next day’s bar.

if it is indeed UTC, converting it to PST, it will be 12/18, but it is showing me 12/19 data for Apple

You don’t need to convert it to PST. Again, the bar contains the trades between ET midnights, in this case between 2024-12-19 midnight and 2024-12-20 midnight.