According to coin market cap litecoin has increased approximately 2000% (YTD). 

What is litecoin and why is it rising in price? 

 Litecoin, like BTC, is a peer-to-peer Internet currency allowing “instant, near-zero cost payments to anyone in the world.”In addition, it is also decentralized without any central authorities. In comparison to BTC, Litecoin is able to process a block every 2.5 minutes while BTC does it in 10 minutes. According to developers, this feature makes Litecoin superior to the BTC. It offers faster transaction confirmation. Additionally, Litecoin is said to offer improved storage efficiency. The following text was obtained from an academic paper:

“Litecoin uses in its proof-of-work algorithm, a sequential memory-hard function requiring asymptotically more memory than an algorithm which is not memory-hard.” Source

Litecoin's rally is best seen not as an isolated event, but part of an increased institutional interest in the crypto currency, triggered by a major rally in bitcoin this year. As it remains best known as the "silver to bitcoin’s gold," the focus of the team behind litecoin has been to promote it as a payment method, especially as bitcoin continues to underperform in this area.As LTC creator Charlie Lee said recently, "Litecoin will provide a niche where it will be more used for payment, whereas bitcoin will be more used for storing."Yet, while it has a smaller network, with fewer merchants and miners, it's also showing signs its technology is advancing more quickly. Litecoin was the first major currency to activate a code upgrade called SegWit on may 10, moreover, SegWit activation opened doors for the Lightning Network on litecoin, which would allow for faster and cheaper transactions.On September 1, Litecoin Foundation tweeted that the first Lightning Network-based litecoin transaction was successful. 

My opinion: to buy or not to buy?

Litecoin, typically mirrors the price action of Bitcoin except with a few alterations. The recent appreciation of bitcoin cash has resulted in a slight dip in the litecoin price. However, with the bitcoin cash price slipping, I believe that is time for litecoin to experience significant gains. In my opinion, litecoin should and eventually will be approximately on quarter of the price of bitcoin and it will therefore easily surpass the $1000 mark in the near to mid term future (between now to the end of  2018). Of course this is a speculative market and if you choose to invest then you are responsible for the risks involved.