Daily Value of Stock Portfolio Postgres
Here you go - just needed to multiply the closing price by the running total of shares:
SELECT 
  pricesclose.Date
 ,pricesclose.ticker
 ,transactions.shares
 ,pricesclose.close
 ,SUM(transactions.shares) OVER (PARTITION BY pricesclose.ticker ORDER BY pricesclose.date) AS totalshares
 ,pricesclose.close * SUM(transactions.shares) OVER (PARTITION BY pricesclose.ticker ORDER BY pricesclose.date) AS marketvalue
FROM 
  pricesclose
LEFT JOIN 
  transactions
    ON pricesclose.ticker = transactions.ticker
        AND pricesclose.date = transactions.transaction_date
ORDER BY 
  pricesclose.date
 ,pricesclose.ticker

Output:
+----------------------+--------+--------+--------+-------------+-------------+
|         date         | ticker | shares | close  | totalshares | marketvalue |
+----------------------+--------+--------+--------+-------------+-------------+
| 2020-01-02T00:00:00Z | IEF    | 36     | 110.73 |          36 | 3986.28     |
| 2020-01-02T00:00:00Z | IVV    | 18     | 326.32 |          18 | 5873.76     |
| 2020-01-03T00:00:00Z | IEF    | (null) | 111.47 |          36 | 4012.92     |
| 2020-01-03T00:00:00Z | IVV    | (null) | 323.81 |          18 | 5828.58     |
| 2020-01-06T00:00:00Z | IEF    | -6     | 111.35 |          30 | 3340.5      |
| 2020-01-06T00:00:00Z | IVV    | (null) | 325.09 |          18 | 5851.62     |
| 2020-01-07T00:00:00Z | IEF    | (null) | 111.19 |          30 | 3335.7      |
| 2020-01-07T00:00:00Z | IVV    | (null) | 324.2  |          18 | 5835.6      |
| 2020-01-08T00:00:00Z | IEF    | (null) | 110.93 |          30 | 3327.9      |
| 2020-01-08T00:00:00Z | IVV    | (null) | 325.85 |          18 | 5865.3      |
+----------------------+--------+--------+--------+-------------+-------------+