How to execute SQL LAG() without being affected by the JOIN clause

Question

I need to get the % change in price of a stock for the dates when the company have dividend exdates.

I have these two tables:

Table 1: Get the prices

 select *
 from prices_table
 where ticker = 'AAPL-US'
order by date desc

Table 2: Get the dividends

select *
from dividends
where ticker = 'AAPL-US'
order by exdate desc

The dates in the prices table are daily (trading dates) while the dividends table only have rows for dates with dividend exdates.

prices table

Date	Ticker	Prices
20240312	AAPL-US	172.75
20240311	AAPL-US	170.73
20240309	AAPL-US	169

dividends table

Exdate	Ticker
20240209	AAPL-US
20231110	AAPL-US
20230811	AAPL-US

I tried the below script using lag() however, the issue is instead of getting the price for the previous trading day before the dividend exdate, it gets the price for the previous exdate:

 select 
 a.ticker
, a.date
, price as current_price
, lag(price, 1) over(order by date asc) as previous_price
,   round(((price - (lag(price, 1) over(order by date asc))) / 
(lag(price, 1) over(order by date asc)) * 100),2) as pct_chg
from price a
join dividends b on a.ticker = b.ticker
and (a.date = b.exdate)
where a.ticker = 'AAPL-US'
order by a.date desc`

data i am expecting:

ticker	date	current price	previous_price	pct_chg
AAPL-US	20240209	188.85	188.32	0.28

May you please help me with what should I tweak with my script?