diff --git a/src/config.rs b/src/config.rs
index a19c4ac..09d3c24 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -43,7 +43,7 @@ impl Config {
         let alpaca_source: Source = env::var("ALPACA_SOURCE")
             .expect("ALPACA_SOURCE must be set.")
             .parse()
-            .expect("ALPACA_SOURCE must be a either 'iex' or 'sip'.");
+            .expect("ALPACA_SOURCE must be 'iex', 'sip', or 'otc'.");
 
         let clickhouse_url = env::var("CLICKHOUSE_URL").expect("CLICKHOUSE_URL must be set.");
         let clickhouse_user = env::var("CLICKHOUSE_USER").expect("CLICKHOUSE_USER must be set.");
@@ -75,6 +75,7 @@ impl Config {
             alpaca_rate_limit: RateLimiter::direct(Quota::per_minute(match alpaca_source {
                 Source::Iex => unsafe { NonZeroU32::new_unchecked(200) },
                 Source::Sip => unsafe { NonZeroU32::new_unchecked(10000) },
+                Source::Otc => unimplemented!("OTC rate limit not implemented."),
             })),
             alpaca_source,
             clickhouse_client: clickhouse::Client::default()
diff --git a/src/threads/data/asset_status.rs b/src/threads/data/asset_status.rs
index b93360a..959c743 100644
--- a/src/threads/data/asset_status.rs
+++ b/src/threads/data/asset_status.rs
@@ -108,7 +108,14 @@ async fn handle_asset_status_message(
                     .await
                     .send(tungstenite::Message::Text(
                         to_string(&websocket::outgoing::Message::Subscribe(
-                            create_websocket_market_message(thread_type, symbols),
+                            match thread_type {
+                                ThreadType::Bars(_) => {
+                                    websocket::outgoing::subscribe::Message::new_market(symbols)
+                                }
+                                ThreadType::News => {
+                                    websocket::outgoing::subscribe::Message::new_news(symbols)
+                                }
+                            },
                         ))
                         .unwrap(),
                     ))
@@ -140,7 +147,14 @@ async fn handle_asset_status_message(
                     .await
                     .send(tungstenite::Message::Text(
                         to_string(&websocket::outgoing::Message::Unsubscribe(
-                            create_websocket_market_message(thread_type, symbols),
+                            match thread_type {
+                                ThreadType::Bars(_) => {
+                                    websocket::outgoing::subscribe::Message::new_market(symbols)
+                                }
+                                ThreadType::News => {
+                                    websocket::outgoing::subscribe::Message::new_news(symbols)
+                                }
+                            },
                         ))
                         .unwrap(),
                     ))
@@ -154,17 +168,3 @@ async fn handle_asset_status_message(
 
     message.response.send(()).unwrap();
 }
-
-fn create_websocket_market_message(
-    thread_type: ThreadType,
-    symbols: Vec<String>,
-) -> websocket::outgoing::subscribe::Message {
-    match thread_type {
-        ThreadType::Bars(_) => websocket::outgoing::subscribe::Message::Market(
-            websocket::outgoing::subscribe::MarketMessage::new(symbols),
-        ),
-        ThreadType::News => websocket::outgoing::subscribe::Message::News(
-            websocket::outgoing::subscribe::NewsMessage::new(symbols),
-        ),
-    }
-}
diff --git a/src/threads/data/backfill.rs b/src/threads/data/backfill.rs
index d02ceac..0faf277 100644
--- a/src/threads/data/backfill.rs
+++ b/src/threads/data/backfill.rs
@@ -3,11 +3,14 @@ use crate::{
     config::{Config, ALPACA_CRYPTO_DATA_URL, ALPACA_NEWS_DATA_URL, ALPACA_STOCK_DATA_URL},
     database,
     types::{
-        alpaca::{api, Source},
+        alpaca::{
+            api::{self, outgoing::Sort},
+            Source,
+        },
         news::Prediction,
         Asset, Bar, Class, News, Subset,
     },
-    utils::{duration_until, last_minute, FIFTEEN_MINUTES, ONE_MINUTE},
+    utils::{duration_until, last_minute, remove_slash_from_pair, FIFTEEN_MINUTES, ONE_MINUTE},
 };
 use backoff::{future::retry, ExponentialBackoff};
 use futures_util::future::join_all;
@@ -251,14 +254,31 @@ async fn execute_backfill_bars(
             app_config
                 .alpaca_client
                 .get(&data_url)
-                .query(&api::outgoing::bar::Bar::new(
-                    vec![symbol.clone()],
-                    ONE_MINUTE,
-                    fetch_from,
-                    fetch_to,
-                    10000,
-                    next_page_token.clone(),
-                ))
+                .query(&match thread_type {
+                    ThreadType::Bars(Class::UsEquity) => api::outgoing::bar::Bar::UsEquity {
+                        symbols: vec![symbol.clone()],
+                        timeframe: ONE_MINUTE,
+                        start: Some(fetch_from),
+                        end: Some(fetch_to),
+                        limit: Some(10000),
+                        adjustment: None,
+                        asof: None,
+                        feed: Some(app_config.alpaca_source),
+                        currency: None,
+                        page_token: next_page_token.clone(),
+                        sort: Some(Sort::Asc),
+                    },
+                    ThreadType::Bars(Class::Crypto) => api::outgoing::bar::Bar::Crypto {
+                        symbols: vec![symbol.clone()],
+                        timeframe: ONE_MINUTE,
+                        start: Some(fetch_from),
+                        end: Some(fetch_to),
+                        limit: Some(10000),
+                        page_token: next_page_token.clone(),
+                        sort: Some(Sort::Asc),
+                    },
+                    _ => unreachable!(),
+                })
                 .send()
                 .await?
                 .error_for_status()?
@@ -325,15 +345,16 @@ async fn execute_backfill_news(
             app_config
                 .alpaca_client
                 .get(&data_url)
-                .query(&api::outgoing::news::News::new(
-                    vec![symbol.clone()],
-                    fetch_from,
-                    fetch_to,
-                    50,
-                    true,
-                    false,
-                    next_page_token.clone(),
-                ))
+                .query(&api::outgoing::news::News {
+                    symbols: vec![remove_slash_from_pair(&symbol)],
+                    start: Some(fetch_from),
+                    end: Some(fetch_to),
+                    limit: Some(50),
+                    include_content: Some(true),
+                    exclude_contentless: Some(false),
+                    page_token: next_page_token.clone(),
+                    sort: Some(Sort::Asc),
+                })
                 .send()
                 .await?
                 .error_for_status()?
@@ -399,7 +420,7 @@ async fn execute_backfill_news(
         })
         .collect::<Vec<_>>();
 
-    let backfill = (news[0].clone(), symbol.clone()).into();
+    let backfill = (news.last().unwrap().clone(), symbol.clone()).into();
     database::news::upsert_batch(&app_config.clickhouse_client, news).await;
     database::backfills::upsert(&app_config.clickhouse_client, &thread_type, &backfill).await;
 
diff --git a/src/threads/data/websocket.rs b/src/threads/data/websocket.rs
index 806ce64..e5b6ba5 100644
--- a/src/threads/data/websocket.rs
+++ b/src/threads/data/websocket.rs
@@ -102,9 +102,8 @@ async fn handle_parsed_websocket_message(
     match message {
         websocket::incoming::Message::Subscription(message) => {
             let symbols = match message {
-                websocket::incoming::subscription::Message::Market(message) => message.bars,
-                websocket::incoming::subscription::Message::News(message) => message
-                    .news
+                websocket::incoming::subscription::Message::Market { bars, .. } => bars,
+                websocket::incoming::subscription::Message::News { news } => news
                     .into_iter()
                     .map(|symbol| add_slash_to_pair(&symbol))
                     .collect(),
diff --git a/src/types/alpaca/api/outgoing/bar.rs b/src/types/alpaca/api/outgoing/bar.rs
index 48b758f..9e1bce9 100644
--- a/src/types/alpaca/api/outgoing/bar.rs
+++ b/src/types/alpaca/api/outgoing/bar.rs
@@ -1,4 +1,5 @@
-use super::serialize_symbols;
+use super::{serialize_symbols, Sort};
+use crate::types::alpaca::Source;
 use serde::Serialize;
 use std::time::Duration;
 use time::OffsetDateTime;
@@ -36,36 +37,60 @@ where
 }
 
 #[derive(Serialize)]
-pub struct Bar {
-    #[serde(serialize_with = "serialize_symbols")]
-    pub symbols: Vec<String>,
-    #[serde(serialize_with = "serialize_timeframe")]
-    pub timeframe: Duration,
-    #[serde(with = "time::serde::rfc3339")]
-    pub start: OffsetDateTime,
-    #[serde(with = "time::serde::rfc3339")]
-    pub end: OffsetDateTime,
-    pub limit: i64,
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub page_token: Option<String>,
+#[allow(dead_code)]
+pub enum Adjustment {
+    Raw,
+    Split,
+    Dividend,
+    All,
 }
 
-impl Bar {
-    pub const fn new(
+#[derive(Serialize)]
+#[serde(untagged)]
+pub enum Bar {
+    UsEquity {
+        #[serde(serialize_with = "serialize_symbols")]
         symbols: Vec<String>,
+        #[serde(serialize_with = "serialize_timeframe")]
         timeframe: Duration,
-        start: OffsetDateTime,
-        end: OffsetDateTime,
-        limit: i64,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        #[serde(with = "time::serde::rfc3339::option")]
+        start: Option<OffsetDateTime>,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        #[serde(with = "time::serde::rfc3339::option")]
+        end: Option<OffsetDateTime>,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        limit: Option<i64>,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        adjustment: Option<Adjustment>,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        #[serde(with = "time::serde::rfc3339::option")]
+        asof: Option<OffsetDateTime>,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        feed: Option<Source>,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        currency: Option<String>,
+        #[serde(skip_serializing_if = "Option::is_none")]
         page_token: Option<String>,
-    ) -> Self {
-        Self {
-            symbols,
-            timeframe,
-            start,
-            end,
-            limit,
-            page_token,
-        }
-    }
+        #[serde(skip_serializing_if = "Option::is_none")]
+        sort: Option<Sort>,
+    },
+    Crypto {
+        #[serde(serialize_with = "serialize_symbols")]
+        symbols: Vec<String>,
+        #[serde(serialize_with = "serialize_timeframe")]
+        timeframe: Duration,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        #[serde(with = "time::serde::rfc3339::option")]
+        start: Option<OffsetDateTime>,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        #[serde(with = "time::serde::rfc3339::option")]
+        end: Option<OffsetDateTime>,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        limit: Option<i64>,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        page_token: Option<String>,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        sort: Option<Sort>,
+    },
 }
diff --git a/src/types/alpaca/api/outgoing/mod.rs b/src/types/alpaca/api/outgoing/mod.rs
index 6293fb8..f26e908 100644
--- a/src/types/alpaca/api/outgoing/mod.rs
+++ b/src/types/alpaca/api/outgoing/mod.rs
@@ -1,7 +1,15 @@
 pub mod bar;
 pub mod news;
 
-use serde::Serializer;
+use serde::{Serialize, Serializer};
+
+#[derive(Serialize)]
+#[serde(rename_all = "camelCase")]
+#[allow(dead_code)]
+pub enum Sort {
+    Asc,
+    Desc,
+}
 
 fn serialize_symbols<S>(symbols: &[String], serializer: S) -> Result<S::Ok, S::Error>
 where
diff --git a/src/types/alpaca/api/outgoing/news.rs b/src/types/alpaca/api/outgoing/news.rs
index 5a3c2ee..2d57614 100644
--- a/src/types/alpaca/api/outgoing/news.rs
+++ b/src/types/alpaca/api/outgoing/news.rs
@@ -1,5 +1,4 @@
-use super::serialize_symbols;
-use crate::utils::remove_slash_from_pair;
+use super::{serialize_symbols, Sort};
 use serde::Serialize;
 use time::OffsetDateTime;
 
@@ -7,38 +6,20 @@ use time::OffsetDateTime;
 pub struct News {
     #[serde(serialize_with = "serialize_symbols")]
     pub symbols: Vec<String>,
-    #[serde(with = "time::serde::rfc3339")]
-    pub start: OffsetDateTime,
-    #[serde(with = "time::serde::rfc3339")]
-    pub end: OffsetDateTime,
-    pub limit: i64,
-    pub include_content: bool,
-    pub exclude_contentless: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    #[serde(with = "time::serde::rfc3339::option")]
+    pub start: Option<OffsetDateTime>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    #[serde(with = "time::serde::rfc3339::option")]
+    pub end: Option<OffsetDateTime>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub limit: Option<i64>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub include_content: Option<bool>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub exclude_contentless: Option<bool>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub page_token: Option<String>,
-}
-
-impl News {
-    pub fn new(
-        symbols: Vec<String>,
-        start: OffsetDateTime,
-        end: OffsetDateTime,
-        limit: i64,
-        include_content: bool,
-        exclude_contentless: bool,
-        page_token: Option<String>,
-    ) -> Self {
-        Self {
-            symbols: symbols
-                .into_iter()
-                .map(|symbol| remove_slash_from_pair(&symbol))
-                .collect(),
-            start,
-            end,
-            limit,
-            include_content,
-            exclude_contentless,
-            page_token,
-        }
-    }
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub sort: Option<Sort>,
 }
diff --git a/src/types/alpaca/source.rs b/src/types/alpaca/source.rs
index f734d3e..948bedc 100644
--- a/src/types/alpaca/source.rs
+++ b/src/types/alpaca/source.rs
@@ -1,12 +1,15 @@
+use serde::{Deserialize, Serialize};
 use std::{
     fmt::{Display, Formatter},
     str::FromStr,
 };
 
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
 pub enum Source {
     Iex,
     Sip,
+    Otc,
 }
 
 impl FromStr for Source {
@@ -26,6 +29,7 @@ impl Display for Source {
         match self {
             Self::Iex => write!(f, "iex"),
             Self::Sip => write!(f, "sip"),
+            Self::Otc => write!(f, "otc"),
         }
     }
 }
diff --git a/src/types/alpaca/websocket/incoming/subscription.rs b/src/types/alpaca/websocket/incoming/subscription.rs
index 7e44d02..2c88085 100644
--- a/src/types/alpaca/websocket/incoming/subscription.rs
+++ b/src/types/alpaca/websocket/incoming/subscription.rs
@@ -1,28 +1,20 @@
 use serde::Deserialize;
 
-#[derive(Clone, Debug, PartialEq, Eq, Deserialize)]
-#[serde(rename_all = "camelCase")]
-pub struct MarketMessage {
-    pub trades: Vec<String>,
-    pub quotes: Vec<String>,
-    pub bars: Vec<String>,
-    pub updated_bars: Vec<String>,
-    pub daily_bars: Vec<String>,
-    pub orderbooks: Option<Vec<String>>,
-    pub statuses: Option<Vec<String>>,
-    pub lulds: Option<Vec<String>>,
-    pub cancel_errors: Option<Vec<String>>,
-}
-
-#[derive(Clone, Debug, PartialEq, Eq, Deserialize)]
-#[serde(rename_all = "camelCase")]
-pub struct NewsMessage {
-    pub news: Vec<String>,
-}
-
 #[derive(Clone, Debug, PartialEq, Eq, Deserialize)]
 #[serde(untagged)]
 pub enum Message {
-    Market(MarketMessage),
-    News(NewsMessage),
+    #[serde(rename_all = "camelCase")]
+    Market {
+        trades: Vec<String>,
+        quotes: Vec<String>,
+        bars: Vec<String>,
+        updated_bars: Vec<String>,
+        daily_bars: Vec<String>,
+        orderbooks: Option<Vec<String>>,
+        statuses: Option<Vec<String>>,
+        lulds: Option<Vec<String>>,
+        cancel_errors: Option<Vec<String>>,
+    },
+    #[serde(rename_all = "camelCase")]
+    News { news: Vec<String> },
 }
diff --git a/src/types/alpaca/websocket/outgoing/auth.rs b/src/types/alpaca/websocket/outgoing/auth.rs
index a8933e5..94b10fb 100644
--- a/src/types/alpaca/websocket/outgoing/auth.rs
+++ b/src/types/alpaca/websocket/outgoing/auth.rs
@@ -2,12 +2,6 @@ use serde::Serialize;
 
 #[derive(Serialize)]
 pub struct Message {
-    key: String,
-    secret: String,
-}
-
-impl Message {
-    pub const fn new(key: String, secret: String) -> Self {
-        Self { key, secret }
-    }
+    pub key: String,
+    pub secret: String,
 }
diff --git a/src/types/alpaca/websocket/outgoing/subscribe.rs b/src/types/alpaca/websocket/outgoing/subscribe.rs
index 465ab62..ef78c28 100644
--- a/src/types/alpaca/websocket/outgoing/subscribe.rs
+++ b/src/types/alpaca/websocket/outgoing/subscribe.rs
@@ -2,30 +2,27 @@ use crate::utils::remove_slash_from_pair;
 use serde::Serialize;
 
 #[derive(Serialize)]
-#[serde(rename_all = "camelCase")]
-pub struct MarketMessage {
-    bars: Vec<String>,
-    updated_bars: Vec<String>,
+#[serde(untagged)]
+pub enum Message {
+    #[serde(rename_all = "camelCase")]
+    Market {
+        bars: Vec<String>,
+        updated_bars: Vec<String>,
+    },
+    #[serde(rename_all = "camelCase")]
+    News { news: Vec<String> },
 }
 
-impl MarketMessage {
-    pub fn new(symbols: Vec<String>) -> Self {
-        Self {
+impl Message {
+    pub fn new_market(symbols: Vec<String>) -> Self {
+        Self::Market {
             bars: symbols.clone(),
             updated_bars: symbols,
         }
     }
-}
 
-#[derive(Serialize)]
-#[serde(rename_all = "camelCase")]
-pub struct NewsMessage {
-    news: Vec<String>,
-}
-
-impl NewsMessage {
-    pub fn new(symbols: Vec<String>) -> Self {
-        Self {
+    pub fn new_news(symbols: Vec<String>) -> Self {
+        Self::News {
             news: symbols
                 .into_iter()
                 .map(|symbol| remove_slash_from_pair(&symbol))
@@ -33,10 +30,3 @@ impl NewsMessage {
         }
     }
 }
-
-#[derive(Serialize)]
-#[serde(untagged)]
-pub enum Message {
-    Market(MarketMessage),
-    News(NewsMessage),
-}
diff --git a/src/types/backfill.rs b/src/types/backfill.rs
index e940d76..92ad587 100644
--- a/src/types/backfill.rs
+++ b/src/types/backfill.rs
@@ -10,20 +10,20 @@ pub struct Backfill {
     pub time: OffsetDateTime,
 }
 
-impl Backfill {
-    pub const fn new(symbol: String, time: OffsetDateTime) -> Self {
-        Self { symbol, time }
-    }
-}
-
 impl From<Bar> for Backfill {
     fn from(bar: Bar) -> Self {
-        Self::new(bar.symbol, bar.time)
+        Self {
+            symbol: bar.symbol,
+            time: bar.time,
+        }
     }
 }
 
 impl From<(News, String)> for Backfill {
     fn from((news, symbol): (News, String)) -> Self {
-        Self::new(symbol, news.time_created)
+        Self {
+            symbol,
+            time: news.time_created,
+        }
     }
 }
diff --git a/src/utils/websocket.rs b/src/utils/websocket.rs
index 5aef8ee..6983bff 100644
--- a/src/utils/websocket.rs
+++ b/src/utils/websocket.rs
@@ -28,10 +28,10 @@ pub async fn authenticate(
     sender
         .send(Message::Text(
             to_string(&websocket::outgoing::Message::Auth(
-                websocket::outgoing::auth::Message::new(
-                    app_config.alpaca_api_key.clone(),
-                    app_config.alpaca_api_secret.clone(),
-                ),
+                websocket::outgoing::auth::Message {
+                    key: app_config.alpaca_api_key.clone(),
+                    secret: app_config.alpaca_api_secret.clone(),
+                },
             ))
             .unwrap(),
         ))