Congratulations si! You found a 100 dollar bill in those pants you haven't worn in 2 yrs. Actually since April 15, 2016. On that date you must have held 1000 shares of Liberty Media (LMCA). Through Spinco, Liberty Media split into 3 tracking stocks, Liberty Braves BATRA, Liberty Sirius XM LSXMA and Liberty Media LMCA. You got 1 for 1 BATRA, 1 for 10 LSXMA, 1 for 4 LMCA and some cash for the fractional LMCA shares. It was a corporate action, not a purchase. Since then Liberty acquired Formula One racing, retained an interest in Live Nation and changed the ticker for Liberty Media from LMCA to FWONA.
If you held it in a taxable account it doesn't incur any tax liability at the time. But will incur cap gains when you sell any of them. This is John Malone at his tax aversion best. The cost basis changed and is different for all 3 holdings. Check out the Liberty webpage ( http://www.libertymedia.com/stock-cost-basis.html ) for that info.
Currently, you're probably looking at a 15% gain in BATRA, 57% in LSXMA, and 30% in FWONA. The LSXMA shares represent Malone's SIRI shares (about 9 for 1) and selling at an 18% discount to SIRI.
Hope this is accurate and helpful.
http://www.libertymedia.com/stock-cost-basis.html