Sorting messes up cell references

(see attachment).
When I sort the table in Sheet1 by the "Latest Equity" column, the "lookup value" in my two MATCH statements gets screwed up and points to the wrong cells. I tried putting in absolute cell references using '$' but that didn't fix it.

Thanks protonLeah, although your different coding fixed it, I couldn't figure out why. Then I saw that your MATCH functions did not contain the sheet reference for the lookup value (which was on the same sheet so a sheet reference was not necessary) and mine did (automatically populated by Excel). When I stripped out the sheet reference to Sheet1 my functions worked fine as well but I cannot figure out why it matters. Can anybody clarify?